Endo Lec 4th

Endodontics
Lec: 1
Introduction
Endo is a Greek word for "Inside" and Odont is Greek for "Tooth".
Endodontic treatment treats inside the tooth.
Endodontics is the branch of clinical dentistry associated with the
prevention, diagnosis and treatment of the pathosis of the dental pulp and
their sequela. Thus we can say that the primary goal of endodontic
therapy is to create an environment within the root canal system which
allows the healing and continued maintenance of the health of the
periradicular tissue.
Endodontics has been defined as art as well as science of clinical
dentistry because in spite of all the factual scientific foundation on which
the endodontic is based, to provide an ideal endodontic treatment is an art
in itself.
History:
Toothache has been a scourge to humanity from the earliest times.
Both the Chinese and the Egyptians left records describing caries and
alveolar abscesses. The Chinese considered that these abscesses were
caused by a white worm with a black head which lived within the tooth.
The Chinese treatment for an abscessed tooth was aimed at killing the
worm with a preparation that contained arsenic. The use of this drug was
taught in most dental schools as recently as the 1950s, in spite of the
realization that it was self- limiting and that extensive tissue destruction
occurred if minute amounts of the drug leaked into the soft tissues.
Pulpal treatment during Greek and Roman times was aimed at
destroying the pulp by cauterization with a hot needle or boiling oil, or
with a mixture of opium and hyoscyamus.
At the end of the first century, it was realized that pain could be
relieved by drilling into the pulp chamber to obtain drainage. In spite of
modern “wonder drugs” there is still no better method of relieving the
pain of an abscessed tooth than drainage.
Endodontic knowledge remained static until the 16 th century when
Pulpal anatomy was described. Before the latter part of the 19 th century,
root canal therapy consisted of alleviating pulpal pain, the injection of 4%
cocaine as a mandibular nerve block was first reported in 1884, and 20
years later the first synthetic local anaesthetic, procaine, was produced.
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Shortly after the discovery of X- rays by Roentgen in 1895, the
first radiograph of teeth was taken. This further popularized root canal
therapy and gave the treatment respectability.
About the same time dental manufacturers began to produce
special instruments which were used primarily to remove pulp tissue or
clean debris from the canal.
By 1910 root canal therapy had reached its zenith and no self-
respecting dentist would extract a tooth. Every root stump was retained
and a crown constructed. Sinus tracts often appeared and were treated by
various ineffective methods for many years. The connection between the
sinus tract and the pulpless tooth was known but no one acted upon it.
Modern Endodontics:
The re-emergence of endodontics as a respectable branch of dental

science began in the 1930s.
Gradually, the concept that a “dead” tooth was not necessarily
infected began to be accepted. Further, it was realized that the function
and usefulness of the tooth depended on the integrity of the periodontal
tissues and not on the vitality of the pulp.
Another important advance was the formulation of the “hollow
tube” theory, which was later questioned in research using sterile
polyethylene tube implants in rats. The tissue surrounding the Lumina of
clean, disinfected tubes, which were closed at one end, was relatively free
of inflammation and displayed a normal capacity for repair. When such
tubes were filled with muscle contaminated with G-ve cocci, the
inflammatory reaction was only severe around the openings of the tubes
containing contaminated muscle. These findings changed the emphasis of
the “hollow tube” theory; stress is now placed on the microbial contents
of the tube. If the tube contains microorganisms then the potential for
repair is far less favorable than when the lumen of the tube is clean and
sterile. This situation is likely to be found in most root canals requiring
treatment.
The concept that “apical seal” was important led to the search for filling
and sealing materials which are stable, non- irritant and provide a perfect
seal at the apical foramen.
In summary, the principles of modern endodontic treatment are:
Clean: remove microorganisms and pulpal debris from the root canal
system.
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Shape: produce a gradual smooth taper in the root canal with the widest
part coronally and the narrowest part 1mm short of the apex.
Fill: obturate the canal system with an inert, insoluble filling material.
Scope of endodontics:
The extent of the subject has altered considerably in the last 50
years. Formerly, endodontic treatment confined itself to root canal filling
techniques by conventional methods, even endodontic surgery, which is
an extension of these methods, was considered to be in the field of oral
surgery. Modern endodontics has a much wider field and includes the
following:
1- Diagnosis of oral pain.
2- Protection of the healthy pulp from disease or injury.
3- Pulp capping (both indirect and direct).
4- Pulpotomy (both conventional and partial).
5- Pulpectomy.
6- Root canal treatment of infected root canals.
7- Surgical endodontics, which include apicectomy, hemisection, root
amputation and replantation.
3
Endodontics
Lec.2 Dr. Iman Mohammed

‫ ﺑﻠﻨﺪ ﻣﺤﻤﺪ ﺳﻠﻴﻢ‬.‫د‬
Basic instrumentation in Endodontics:-

It is now widely accepted that success in root canal treatment
depends upon the thorough cleaning & shaping of the root canal system
& the placement of a three- dimensional root canal filling of gutta-percha
& inert sealer. To fulfill these objectives, many different instruments each
with a specific purpose, must be available. Some of these instruments
have been used for many years, whilst others are newer & highly
technical.
 Endodontic Explorer:-
The straight end of the explorer is designed to aid in location of
root canal orifices, its tip is sharp & able to negotiate a small opening, the
instrument has sufficient rigidity to explore with controlled force. The L-
shaped end aids in detection unremoved portions of the pulp chamber
root.
 Plastic Instrument:-
The blade like end of this instrument is used to carry & place the
temporary filling materials. The opposite end is used as a plugger to
condense filling materials in the pulp chamber.
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 Endodontic excavator:-
The shape of this instrument allows curettage of the pulp chamber
when conventional excavator will not reach the floor of the chamber (had
long shank). It’s also part of the surgery kit and is used to curette
periapical lesion.
 Endodontic locking plier:-

It has a latch that permits materials to be held without continuous
finger pressure. The grooved tips facilitate holding absorbent points and
gutta-percha cones, which tend to loosen in ungrooved tips.
 Endodontic ruler:-
The 0.5 mm ruler is a convenient instrument with which to
measure files, gutta-percha cones, and also we have a measuring blocks
and special millimeter thumb rulers.
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 Endodontic syringe:-
It’s used to carry the irrigants into the root canal. The needle tip is
flat to prevent penetration into smaller canal diameter and grooved to
allow irrigants that may be under pressure to flow coronolly rather than
be forced through the apical foramen. When drying canals, most of the
irrigant may be aspirated from the canal by pulling back on the plunger.
 Instrument organizer:-
A means of organizing endodontic files according to size and
length is a necessity. The organizer provides holes for the files, which are
held vertically in a sponge allowing them to be grasped easily. The
sponge is saturated with disinfectant solutions that maintain instrument
sterility.
 Transfer sponge:-
A banker’s sponge is a convenient aid to
hold files during root canal preparation. As an
assistant or the dentist adjusts the elastic stops
on each file. The instruments are placed in the
sponge according to size. Each file is then easily
grasped, used and replaced in the sponge. The
sponge, which is saturated with disinfectant
solution, also is useful to debride the instrument.
If, during canal preparation, debris and dentin
shaving accumulate on the file, they are easily
removed by inserting the file into the sponge a
few minutes.
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 Instrument stop:-
After the canal length is determined, it’s necessary to mark that
length on the file. This is accomplished by placing an elastic stop on the
instrument shaft. Silicone stops are available commercially, or instrument
stops can be made easily by cutting a rubber band into 2 mm squares,
which are then centered on the instrument shaft.
When placing the stop on the instrument, it’s important to avoid

angulation which may measure different lengths as the file is rotated. The
test handle is an adjustable handle that can be moved on the instrument
shaft and locked at a specific length. The assembly consists of a file shaft
placed in a handle and nut. Once the correct length is set, the bulky
handle provides a mechanical stop that prevents the instrument from
extending beyond the measured length. For this reason, the test handle is
useful to prevent unintentional instrumentation through the apical
foramen.
 Burs:-
Several types of bur will be required to accomplish good access
preparation.
1. Round bur: - round burs, normal and extra-long, size 2, 4,
and 6, are used to lift the roof off the pulp chamber and
eliminate over-hanging dentin. The longer and smaller sizes
can be used to find calcified canals.
2. Safe-ended burs:- A safe-ended diamond or tungsten-
carbide bur, the Endo-Z bur, both with a non-cutting tip, is
used to taper & smooth the access cavity preparation. The
non-cutting tip prevents gouging on the floor of the pulp
chamber, where important landmarks could be lost in
pinpointing the location of root canals.
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 Hand Spreader:-
Manufactured from stainless steel, land spreaders are designed to
facilitate the placement of accessory gutta-percha points around a well-
fitting master gutta-percha point during the lateral condensation method.
Their diameter & shape are not standardized making it difficult to match
spreaders with accessory gutta-percha points.
 Finger spreaders:-
These instruments are color-coded to match either standardized or
accessory gutta-percha points. Their short length affords a high degree of
tactile sense & allows them to rotate freely around their axis, thus freeing
the instrument for easy removal.
The depth of spreader penetration is important for the quality of the
find apical seal; spreaders should be capable of reaching to within 1-2
mm of the apical stop alongside its master gutta-percha point.
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Endodontic Pluggers:-
Endodontic pluggers consist of long-handled instruments which are
of larger diameter than spreaders & have a blunt end; they are used to
pack thermally softened gutta-percha into the root canal. The different-
diameter pluggers have reference lines on the tips to allow the assessment
of plugger depth. It’s very important to realize when the plugger is
engaging a cushion of softened gutta-percha, rather than the resistance of
the canal wall. These pluggers may also be used to pack calcium
hydroxide into root canals.
6
Endodontics
‫ ﺑﻠﻧد ﻣﺣﻣد ﺳﻠﻳﻡ‬.‫د‬
Lec:3 Dr. Iman Mohammed
Hand instruments
Hand instruments are grouped according to usage by the
International Organization for Standardization (ISO),
working alongside the American National Standards Institute
(ANSI). These organizations have defined terminology,
dimensions, physical properties, measuring systems and quality
control of endodontic instruments and materials.
Standardization:-
The development of world wide standards for endodontic
instruments and materials has occurred since the 1950s, when it
was realized that a considerable amount of variation existed
between root canal instruments of different manufacturers. At
that time proposals for standardizing instruments were produced
and covered the following:-
1) The diameter and taper of each instrument and filling
point.
2) The graduated increase in size from one instrument to the
next.
3) An instrument- numbering system based on the diameter
of the instrument.
These proposals have been widely accepted, and
endodontic hand instruments, (files, reamers and barbed
broaches) are standardized in relation to size, color coding and
physical properties.
The guidelines for instruments are:
1-Instruments are numbered from 06-150.Each number
represent diameter of instrument in 100th of millimeter at the
tip.
2-Working blade begins at tip (D1) and extends 16 mm up the
shaft (D2). D1 represents the diameter of the projection of the
working part at the tip end, and is its nominal size. (D2) is 0.32
1
mm greater than D1, ensuring
that there is constant increase
in taper, i.e 0.02mm per mm
of instrument.
3-Tip angle of instrument
varies as 75+_ 150.
4-Instrument handles are
color coded for their easier
recognition (yellow, red).
5-Instrument available in length 21, 25, 28, and 30mm are used
for root canal therapy.
Barbed broaches:-
These are made from soft steel wire. The barbs are formed
by cutting into the metal and forcing the cut portion away from
the shaft, so that the tip of the barb points towards the
handle. The cuts are made eccentrically around the
shaft so that it’s not weakened excessively at any one
point. Barbed broaches are mainly used for the
removal of pulp tissue from root canals, but also for
removal of cotton- wool dressings.
Provided the instrument is loose within the canal and
the barb is used to engage soft tissue only, the risk of
fracture is minimal. However, as soon as the barbed
broach is wedged against the wall of the canal, the
barbs are flattened against the shaft. When an attempt
is made to remove the instrument from the canal, the
sharp barb tips dig into the canal wall and resist its withdrawal.
Considerable force may be necessary to free the jammed
instrument and there is a risk of either fracturing the shaft of the
instrument or at least some of the individual delicate barbs. For
this reason, the instrument should never be used to shape canal
walls.
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Reamers:-
Reamers are usually made from stainless steel by twisting
tapered lengths of wire which have a triangular or square cross-
section, to form an instrument with sharp
cutting edges along the spiral. Although cross-
section is a manufacturer’s prerogative, the
smaller sizes (15-50) are usually
manufactured from a square blank, while the
larger sizes are manufactured form a
triangular blank. Reamers are used to enlarge
and shape an irregularly shaped root canal
into a cavity of round cross- section. The
basic action is a half- turn twist and pull
which shaves the canal, removing dentine
chips from the root canal. However, anatomically, no root canal
is round in cross- section and none can be prepared. Reamers are
widely used in cleaning and shaping procedures, and during the
method of canal preparation.
Files:-
There are various types of root canal file, and they are
usually made from stainless steel. The followings are the main
types:-
1)K-file. 2) K-flex. 3) Flexofile. 4) Flex-R. 5) Hedstrom and
Safety Hedstrom. 6) S-file.
Files are predominantly used with a filing or rasping action, in
which there is little or no rotation of the instrument in the root
canal, except for the Flex-R instrument.
K-file:-
This instrument is manufactured from
stainless-steel wire which is ground into square
or triangular cross-section. The blank is twisted
into a tighter series of spirals than a reamer to
produce from 0.9 to 1.9 cutting edges per
millimeter length; some K-files are ground.
When a K-file is manufactured from a
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triangular cross-section it demonstrates superior cutting
efficiency, and as a result of its increased flexibility is more
likely to follow canal curvature than a file with a square cross-
section.
K-flex file:-
The K-flex file has a cross-section that is rhomboid-
shaped and the twisted instrument has a series of
cutting flutes with alternate sharp (< 60°) cutting
edges and obtuse non-cutting edges. The cutting
efficiency of the K-flex file is greater than many
brands of K-file; due to its increased flexibility
and ability to remove debris as its alternating
blades provide a reservoir for debris, also the decrease in
contact of instrument with canal walls provides more space for
irrigation. A disadvantage of this file is its quicker loss of
cutting efficiency.
Flexofile:-
This instrument is manufactured by maillefer in the same
manner as the K-file but it has a triangular cross-section that
gives sharper cutting blades and more room for debris than the
conventional K-file. The stainless steel is extremely flexible and
the instrument resists fracture. The file tip is non-cutting
(Butt).
A- K-file B- K-Flex file C- Flex-o-file
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Flex-R file:-
Most root canal instruments have a sharp tip. Removal of
the sharp cutting edges form the tip of the instrument helps to
prevent undesirable ledge formation. The flex-R design
eliminates the possibility of ledge formation by removing the
cutting surfaces at the tip’s leading edge. This enables the tip
to ride along the canal rather than gouge into it. At the same
time, the triangular cross-sectional area of the flex-R provides
flexibility to negotiate severely curved canals.
Hedstrom and Safety Hedstrom:-

The hedstrom file is made by machining a
steel blank of round cross-section to produce
elevated cutting edges. The tapering effect appears
to form a series of intersecting cones. Although
the design leads to a flexible instrument, the
instrument is inherently weak due to the small
shaft diameter and is therefore prone to breakage.
The hedstrom file has been reported to have a low
cutting efficiency compared with other files as it
only cuts on the withdrawal stroke, never the less
it can be used to flare canal orifices and remove
broken instruments, gutta-percha and silver points.
The safety hedstrom file (Kerr) features a non-cutting safety
side along the length of the blade, which reduces the potential
for strip perforations. The non-cutting side is oriented to the side
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of the canal where cutting is not desired, and is indicated by a
flattened side on the handle. The file is used with a traditional
filing technique.
S-file (Unifile):-
Originally developed in Sweden, this
instrument has an S-shaped cross-section which
has been produced by grinding. This results in a
stiffer instrument than the conventional hedstrom
file. A millimeter scale is etched onto the shaft of
the instrument to facilitate length control. The
instrument has good cutting efficiency in either a
filing or reaming action; the instrument therefore
could be classified as a hybrid design.
New instrument design and technology:-

Nickel-titanium file:-
In 1988, the properties of a file
manufactured from nickel-titanium (Ni-Ti)
alloy were reported this file demonstrates greater
elastic flexibility in bending, and greater
resistance to torsional fracture than stainless
steel. There are now several commercial
versions. Ni-Ti files have a non-cutting tip,
cannot be precurved, and tend to straighten
curved root canals less than stainless steel file.
Golden-mediums:-
Maillefer have produced a series of intermediate-size
instruments to complement ISO standard-size instruments. The
new instruments roughly correspond in size to halfway between
standard ISO sizes and are numbered 12, 17, 22, 27, 32, and 37.
Whilst this system addresses the problem of two few
instruments in the smaller sizes, it does not achieve linear
dimensional change at D1. Golden-Mediums are part of the
flexo-file range.
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MAC files and Double MAC files:-
The MAC file is a new
instrument manufactured from
Ni-Ti, and has a working surface
demonstrating dissimilar helical
angles with blades that spiral
round the shaft at different rates.
According to the manufacturer
this allows the instrument to
stay relatively loose within the
canal and balances the forces of the file against the canal wall
during rotation to prevent canal transportation. The Double
MAC has a series of increasing tapers from 0.03 to 0.55
mm/mm length.
Canal Master U:-

The Canal Master U (CMU) hand
instrument was developed in the late
1980s. The instrument is used to
prepare the apical third of the canal,
and has a non-cutting pilot tip, a 1 mm
length cutting blade, and a parallel
sided shaft with a smaller diameter than
the cutting blade. It’s designed to
improve debris removal and reduce
apically extruded debris, further; it
has been reported to create a well-
centered canal preparation without ledging and transportation.
Recently, a Ni-Ti CMU hand instrument has been developed,
and it produces a better canal preparation than other files.
Flexogate:-
Similar in design and use to the CMU hand instrument, the
flexogate is a logical development of the Gates-Glidden drill.
Whereas the latter is used during conventional coronal
preparation of the canal, the flexogate’s task is enlarging the
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apical region of the canal. The flexogate demonstrates a non-
cutting guiding tip and debris evacuation zone which helps to
maintain root canal configuration during instrumentation.
Whilst the flexogate can fracture more easily during
torsion than the CMU, it has a breakage pint approximately 16
mm from the tip, which ensures its retrieval in the event of
separation. The bending moment of the flexogate and the CMU
are well below standard’s specifications for files, leading to
considerable flexibility in curved canals.
8
Endodontics
Lec: 4 Dr. Iman Mohammed
Access opening:
Endodontics cavity preparation may be separated into two
anatomic divisions:-
a- Coronal preparation.
Basic coronal instruments:-
1) The correct burs are
mounted by the dental
assistant prior to their use.
Rarely should a bur have to
be placed or changed during
the operation. For initial
entrance through the enamel
surface or through a
restoration, the ideal cutting
instrument is the round
(carbide or diamond) bur or tapered fissure bur is used to penetrate
through the enamel and slightly into the dentin (approximately
1mm). The high speed handpiece is used for its cutting efficiency.
.
2) As soon as the enamel or restorative penetration and
minor surface extensions are complete, the
accelerated handpiece is put aside, and the slow-
speed (3.000 to 8.000 rpm) contra-angle handpiece
is used, mounted with a round bur. Three sizes of
round burs, No.s 2, 4, and 6, and two lengths,
regular and surgical, are routinely used. The regular-
length round bur in a conventional latch-type contra-
angle handpiece will reach 9 mm from the nose of
the contra-angle. The surgical-length bur will reach
14 or 15 mm and is necessary in some deep
preparations.
3) The round burs are for dentin removal in both anterior
and posterior teeth. These burs are first used to drill
through the dentin and drop into the pulp chamber. The
same bur is then employed in the removal of the roof at
the pulp chamber. The choice of the size of the round
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bur is made by estimating the canal width and chamber size and
depth apparent in the initial radiograph.
* The No. 2 round bur is generally used in preparing mandibular

anterior teeth and most maxillary premolar teeth with narrow
chambers and canals. It's also occasionally used in the incisal pulp
horn area of maxillary anterior teeth. The No. 4 round bur is
generally used in the maxillary anterior teeth and the mandibular
premolar teeth. It's also occasionally used in young maxillary
premolars and adult molars in both arches, that is, molars with
extensive secondary dentin. The No. 6 round bur is used only in
molars with large pulp chamber. A No. 1 round bur is also
occasionally used in the floor of the pulp chamber to seek
additional canal orifices.
4) As soon as the bulk of the overhanging dentin is
removed from the roof of the chamber, the slower
operating round burs are put aside, and once again,
the high-speed fissure bur is used to finish and slope
the side walls in the visible portions of the
preparation. It's safe-ended and will not scar the
pulpal floor. Moreover, it's longer bladed (9mm) for
sloping and funneling the access cavity.
P.S.:- high-speed burs should not be used to penetrate
into, or initially enlarge, the pulp chamber unless the operator is
skilled in endodontic preparations.
In this operation, the clinician
depends almost entirely on the
"feel" of the bur deep inside the
tooth, against the roof and walls of
the pulp chamber, to judge the
extensions that are necessary.
High-speed equipment is operated
by sight alone and is not generally
employed in a blind area where
reliance on tactile sensation is
necessary.
5) Once the orifices have been located, they should be

flared or enlarged and blended into the axial walls of
the access cavity. This process permits the intracanal
instruments used during shaping and cleaning to enter
the canal(s) easily and effortlessly. Gates-Glidden burs
can be used for this purpose, starting with smaller sizes
2
and progressing to the larger sizes. More recently, #.12 tapered
rotary endodontic files have been used for the flaring.
Principles of endodontic cavity preparation:-

Any discussion of cavity preparation must ultimately revert to the
basic principles of cavity preparation established by G.V. Black. Black's
principles are therefore divided into the following:-
Endodontic coronal cavity preparation:-

I- Outline form.
II- Convenience form.
III- Removal of the remaining carious dentin (and defective
restorations).
IV- Toilet of the cavity.
Endodontic Radicular cavity preparation:-

I & II- Outline form and convenience form.
III- Toilet of the cavity.
IV- Retention form.
V- Resistance form.
Principle I: Outline form

The outline form of the endodontic cavity must be correctly shaped
and positioned to establish complete access for instrumentation, from
cavity margin to apical foramen. Moreover, external outline form evolves
from the internal anatomy of the tooth established by the pulp.
To achieve optimal preparation, three factors of internal anatomy
must be considered:-
1) Size of the pulp chamber: - the outline form of endodontic access
cavities is materially affected by the size of the pulp chamber. In
young patients, these preparations must be more extensive than in
older patients, in whom the pulp has receded and the pulp chamber
is smaller in all three dimensions.
2) Shape of pulp chamber: - the finished outline
form should accurately reflect the shape of
the pulp chamber. For example, the floor of
the pulp chamber in a molar tooth is usually
triangular in shape, owing to the triangular
position of the orifices of the canals. This
triangular shape is extended up the walls of
the cavity and out onto the occlusal surface,
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hence, the final occlusal cavity outline form is generally
triangular. As another example, the coronal pulp of a maxillary
premolar is flat mesiodistally but is elongated buccolingually. The
outline form is, therefore, an elongated oval that extends
buccolingually rather than mesiodistally, as does Black's operative
cavity preparation.
3) Number, position, and curvature of root canals:- this factor
regulating outline form is the number, position, and curvature or
direction of the root canals. To prepare each canal efficiently
without interference, the cavity walls often have to be extended to
allow an unstrained instrument approach to the apical foramen.
When cavity walls are extended to improve instrumentation, the
outline form is materially
affected.
Principle II: - convenience form

Convenience form was conceived by Black as a modification of the
cavity outline form to establish greater convenience in the placement of
intracoronal restorations. In endodontic therapy, convenience form makes
more convenient (and accurate) the preparation and filling of the root
canals. Four important benefits are gained through convenience form
modifications:-
1- unobstructed access to the canal orifice:-
In endodontic cavity preparations of all teeth,
enough tooth structure must be removed to
allow instruments to be placed easily into the
orifice of each canal without interference from
overhanging walls. The clinician must be able
to see each orifice and easily reach it with the
instrument points. Failure to observe this
principle not only endangers the successful
outcome of the case but also adds materially to
the duration of treatme
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P.S.: Variations from the normal number of canals:-
A) The lower incisors are a case in point. May have two canals;
one labially and the other one lingually.
B) High incidence of a second separate canal in the mesiobuccal
root of maxillary molars.
C) A second canal often is found in the distal root of mandibular
molars as well.
D) The premolars, both maxillary and mandibular, can also be
counted on to have extra canals.
2- direct access to the apical foramen:-

To provide direct access to the apical foramen,
enough tooth structure must be removed to allow the
endodontic instruments freedom within the coronal
cavity so they can extend down the canal in an
unstrained position. This is especially true when the
canal is severely curved or leaves the chamber at an
obtuse angle.
3- Extension to accommodate filling techniques:-

It's often necessary to expand the outline form to make certain
filling techniques more convenient or practical. If a softened gutta-
percha technique is used for filling, where in rather rigid pluggers
are used in a vertical thrust, then the outline form may have to be
widely extended to accommodate these heavier instruments.
4- Complete authority over the enlarging instrument:-

It's imperative that the clinician maintain complete control over the
root canal instrument. If the instrument is impinged at the canal
orifice by tooth structure that should have been removed, the
dentist will have lost control of the direction of the tip of the
instrument, and the intervening tooth structure will dictate the
control of the instrument. If, on the other hand, the tooth structure
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is removed around the orifice so that the instrument stands free in
this area of the canal, the instrument will then be controlled by only
two factors; the clinician's fingers on the handle of the instrument
and the walls of the canal at the tip of the instrument. Nothing is to
intervene between these two points.
Principle III: - removal of the remaining carious dentin and defective

restorations
Caries and defective restorations remaining in an endodontic cavity
preparation must be removed for three reasons:-
1) To eliminate mechanically as many bacteria as possible
from the interior of the tooth.
2) To eliminate the discolored tooth structure, that may
ultimately lead to staining of the crown.
3) To eliminate the possibility of any bacteria-laden saliva
leaking into the prepared cavity. The
last point is especially true of
proximal or buccal caries that extend
into the prepared cavity.
If the caries is so extensive that the lateral
walls are destroyed, or if a defective restoration is in
place that is loose and leaking, then the entire wall or
restoration should be removed and later restored. It's
important that restoration be postponed until the
radicular preparation has been completed. It's much
easier to complete the Radicular preparation through
an open cavity than through a restored crown. As a
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matter of fact, the more crown that is missing, the easier the radicular
preparation becomes. The ultimate in ease of operation is the molar tooth
broken off at the gingival level.
Principle IV: - toilet of the cavity

All of the caries, debris, and necrotic material must be removed
from the chamber before the radicular preparation is begun. If the
calcified or metallic debris is left in the chamber and carried into the
canal, it may act as an obstruction during canal enlargement. Soft debris
carried from the chamber might increase the bacterial population in the
canal. Coronal debris may also stain the crown, particularly in anterior
teeth.
Round burs, of course, are most helpful in cavity toilet. The long-
blade, endodontic spoon excavator is ideal for debris removal. Irrigation
with sodium hypochlorite is also an excellent measure for cleaning the
chamber and canals of persistent debris.
The chamber may finally be wiped out with cotton, and a careful
flush of air will eliminate the remaining debris. However, air must never
be aimed down the canals. Emphysema of the oral tissues has been
produced by a blast of air escaping out of the apex.
Thank you
7
Endodontics
Lec:5 Dr. Iman Mohammed
Access opening of anterior teeth:-
A- Entrance is always gained through the

lingual surface of all anterior teeth. Initial
penetration is made in the exact center of
the lingual surface at the position marked
"X". A common error is to begin the cavity
too far gingivally.
B- Initial entrance is prepared with a round-

point tapering fissure bur (or round bur)
in an accelerated-speed contra-angle
handpiece with water coolant, operated at a
right angle to the long axis of the tooth.
Only enamel is penetrated at this time. Do
not force the bur; allow it to cut its own
way.
C- Convenience extension toward the incisal

continues the initial penetrating cavity
preparation. Maintain the point of the bur
in the central cavity and rotate the
handpiece toward the incisal so that the bur
parallels the long axis of the tooth. Enamel
and dentin are beveled toward the incisal.
Entrance into the pulp chamber should not
be made with an accelerated-speed instrument. Lack of
tactile sensation with these instruments precludes their use
inside the tooth.
D- The preliminary cavity outline is funneled

and fanned incisally with a fissure bur.
Enamel has a short bevel toward the
1
incisal, and a "nest" is prepared in the dentin to receive the
round bur to be used for penetration.
E- A surgical length No.2 or 4 round burs in a

slow-speed contra-angle handpiece is used to
penetrate the pulp chamber. If the pulp has
greatly receded, a No.2 round bur is used for
initial penetration. Take advantage of
convenience extension toward the incisal to
allow for the shaft of the penetrating bur,
operated nearly parallel to the long axis of the
tooth.
F- Once the pulp chamber has been penetrated,

the remaining roof is removed by catching the
end of a round bur under the lip of the dentine
roof and cutting on the burs withdrawal stroke
(Working from inside the chamber to outside).
G- Once the orifice(s) has been identified and confirmed, the

lingual shoulder is removed. This is the lingual shelf of
dentin that extends from the cingulum to a
point approximately 2mm apical to the orifice.
The lingual shoulder can be removed with a
tapered safety-tip diamond or carbide bur. The
tip of a fine safety-tip diamond bur is placed
approximately 2mm apical to the canal orifice
and inclined to the lingual during rotation to
slope the lingual shoulder. The clinician must be careful
when using this bur to avoid placing a bevel on the incisal
edge. The lingual "shoulder" is removed to give
continuous, smooth-flowing preparation.
H- Occasionally, a No.1 or 2 round bur must be used laterally

and incisally to eliminate pulpal horn debris and bacteria,
this also prevents future discoloration.
2
I- Final preparation relates to the internal anatomy of the
chamber and canal. In a "young" tooth with
a large pulp, the outline form reflects a
large triangular internal anatomy- an
extensive cavity that allows thorough
cleansing of the chamber as well as passage
of large instruments and filling materials
needed to prepare and fill a large canal.
Cavity extension toward the incisal allows greater access
to the midline of the canal.
J- Cavity preparations in "adult" teeth, with the chamber

obturated with secondary dentin, are ovoid in shape.
Preparation funnels down to the orifice of the canal. The
further the pulp has receded, the more difficult it is to
reach to this depth with a round bur. Therefore, when the
radiograph reveals advanced pulpal recession,
convenience extension must be advanced further incisally
to allow the bur shaft and instruments to operate in the
central axis.
K- Final preparation with the reamer in place, the
instrument shaft clears the incisal cavity
margin and reduced lingual "shoulder",
allowing an unrestrained approach to the
apical third of the canal. The instrument
remains under the optimal, round, tapered
cavity may be prepared in the apical third,
tailored to the requirements of round, tapered
filling materials to follow. The remaining
ovoid part of the canal is cleaned and shaped
by circumferential filling or Gates-Glidden
drills.
3
P.S.:- In Maxillary canine, extensive, ovoid,
funnel-shaped preparation must be nearly
as large as for a young tooth. A beveled
incisal extension carries preparation
nearer the central axis, allowing better
access to the curved apical third.
Discovery by exploration of an apical
labial curve calls for even greater incisal
extension.
Errors in cavity preparation:-

1) Perforation at the labiocervical caused by failure to
complete convenience extension toward the incisal, prior
to the entrance of the shaft of the bur.
2) Gouging of the labial or distal wall caused by failure to
recognize the lingual- axial or mesial-axial inclination of
the tooth.
3) Pear-shaped preparation of the apical canal caused by
failure to complete convenience extensions. The shaft of
the instrument rides on the cavity margin and lingual
"shoulder". In adequate debridement and obturation ensure
failure.
4) Discoloration of the crown caused by failure to remove
pulp debris. The access cavity is too far to the gingival
with no incisal extension.
5) Ledge formation at the apical-labial curve caused by
failure to complete the convenience extension. The shaft
of the instrument rides on the cavity margin and
"shoulder".
4
Access opening of premolar teeth:-
A- Entrance is always gained through the occlusal
surface at all posterior teeth. Initial penetration is
made parallel to the long axis of the
tooth in the exact center of the central
groove between the cusp tips of the
maxillary premolars. In mandibular
first premolars the staring location is
halfway up the lingual incline of the
buccal cusp on a line connecting the
cusp tips mandibular second premolars
require less of an adjustment because they have less
lingual inclination.
B- A regular-length No.2 or 4 round bur

is used to open into the pulp chamber.
The bur will be felt to "drop" when the
pulp chamber is reached. If the
chamber is well calcified and the
"drop" is not felt, vertical penetration
is made until the contra-angle
handpiece rests against the occlusal
surface. This depth is approximately 9mm, the
position of the floor of the pulp chamber that lies at
the cervical level. In removing the bur, the orifice is
widened buccolingually to twice the width of the bur
to allow room for exploration for canal orifices. If a
surgical-length bur is used, care must be exercised
not to perforate the furca.
C- An endodontic explorer is used to locate

orifices to the buccal and lingual canals in
the first premolar or the central canal in
the second premolar. Tension of the
explorer shaft against the walls of
preparation will indicate the amount and
direction of extension necessary.
5
D- Working from inside the
pulp chamber to outside, a
round bur is used at low
speed to extend the cavity
buccolingually by
removing the roof of the
pulp chamber.
E- Buccolingual extension
and finish of cavity walls
are completed with a 701U
fissure bur at accelerated
speed.
F-Final preparation should

provide unobstructed access to
canal orifices. Cavity walls
should not impede complete
authority over enlarging
instruments.
G-Outline form of final preparation will be identical for

both newly erupted and "adult" teeth. Buccolingual
ovoid preparation reflects the anatomy of the pulp
chamber and the position of the buccal and lingual canal
orifices. The cavity must be extensive enough to allow
for instruments and filling materials needed to enlarge
and fill canals. Further exploration at this time is
imperative. It may reveal the orifice to an additional
canal, a second canal in the second premolar, or a third
canal in the first premolar.
6
Mandibular Premolars:
*-slight variations exist between mandibular and maxillary
premolars because of the lingual tilt of mandibular premolars.
*the access cavity in these teeth should have extended on to the
buccal cusp tip, in order to gain straight line access.
Errors in cavity preparation:-

1) Under extended preparation exposing only pulp horns.
Control of enlarging instruments is abdicated to cavity
walls. The white color of the roof of the chamber is a
clue to a shallow cavity.
2) Over extended preparation from a fruitless search for a
receded pulp. The enamel walls have been completely
undermined. Gouging relates to failure to refer to the
radiograph, which clearly indicates pulp recession.
3) Perforation at the mesiocervical indentation. Failure to
observe the distal-axial indentation of the tooth led to
bypassing receded pulp and perforation. The maxillary
first premolar is one of the most commonly perforated
teeth.
4) Incomplete preparation and possible instrument breakage
caused by total loss of instrument control. Use only
occlusal access, never buccal or proximal access.
7
Average length of permanent teeth
Tooth Average Canal Root curvature
length
1 1 23mm One canal 100% Straight 75%
Distal curve 53%,

2 2 22.8mm One canal 100%
straight 30%
3 3 Distal curve 32%,

26mm One canal 100%
straight 39%
One canal/ one foramen

Straight 60%
70%
21.5mm
1 1 two canals/ one foramen
Distal curve 23%
23%
One canal/one foramen
Straight 60%
57%
22.4mm
2 2 Two canals/two foramina
Distal curve 23%
30%
Straight 68%, distal

3 3 25mm One canal 94%
curve 20%
Two canals/ two

Straight 38%
foramina 72%
21.8mm
4 4 Two canals/one foramen
Distal curve 37%
13%
One canal/one foramen Distal curve 27%,
75% buccal curve 12.7%
21mm
5 5
Two canals/two foramina Bayonet curve 20.6%

Straight 48%
73.5%
22mm
4 4 Two canals/two foramina
Distal curve 35%
19.5%
Straight 39%
85.5%
5 5 21.4mm
Two canals/two foramina
8 Distal curve 40%
11.5%
9
Endodontics
Lec.6 ‫ ﺑﻠﻨﺪ ﻣﺤﻤﺪ ﺳﻠﻴﻢ‬.‫د‬
Dr. Iman Mohammed
Access opening of posterior teeth:-

 Maxillary molar teeth:-
A- Entrance is always gained
through the occlusal
surface of all posterior
teeth. Initial penetration is
made in the exact center
of the mesial pit, with the
bur directed toward the
lingual. The 702 U tapering fissure bur in an accelerated-
speed contra-angle handpiece is ideal for perforating gold
casting or virgin enamel surface to the depth of dentin.
Amalgam fillings are penetrated with a No.4 or 6 round
bur operating in a slow-speed contra-angle handpiece.
B- According to the size of the chamber, a regular-length

No.4 round bur is used to open into the pulp chamber. The
bur should be directed toward the orifice of the palatal
canal or toward the mesiobuccal canal orifice, where the
greatest space in the chamber exists. It
will be felt to "drop" when the pulp
chamber is reached. If the chamber is
well calcified, initial penetration is
continued until the contra-angle rests
against the occlusal surface. This depth
of 9mm is the usual position of the
floor of the pulp chamber, which lies
at the cervical level. Working from
inside out, back toward the buccal, the
bur removes enough roof of the pulp
chamber for exploration.
1
C- An endodontic explorer is used to
locate orifices of the palatal,
mesiobuccal, and distobuccal canals.
Tension of the explorer against the
walls of preparation will indicate the
amount and direction of extension
necessary. Orifices of canals form
the perimeter of preparation. Special
care must be taken to explore for a
second canal in the mesiobuccal root.
D- Again, wording at slow speed from

inside to outside, a round bur is used
to remove the roof of the pulp
chamber. Internal walls and floor of
preparation should not be cut into
unless difficulty is encountered in
locating orifices. In that case,
surgical-length No.2 round burs are
necessary to explore the floor of the
chamber. Internally, the access cavity
should have all
orifices positioned
entirely on the
pulp floor and
should not extend
into an axial wall.
Extension of an
orifice into the
axial wall creates a mouse hole effect, which indicates
internal underextension and impedes straight-line access.
In such cases the orifice must be repositioned onto the
pulp floor without interference from the axial
E- In posterior teeth the internal impediments are the cervical

dentine bulges and natural coronal canal constriction. The
2
cervical bulges are shelves of dentin that frequently
overhang orifices in posterior teeth, restricting access into
root canals. These bulges can be removed with safety tip
diamond or carbide burs. Final finish and funneling of
cavity walls are completed with a 702U fissure bur or
tapered diamond points at accelerated speed.
F- Final preparation provides unobstructed access to canal
orifices and should not impede complete authority of
enlarging instruments. Improve ease of access by
"leaning" the entire preparation toward the buccal, for all
instrumentation is introduced from the buccal. Notice that
the preparation extends almost to the length at the buccal
cusps. The walls are perfectly smooth, and the orifices are
located at the exact pulpal-axial angles of the cavity floor.
G- Extended outline form reflects the anatomy of the pulp
chamber. The base is towards the buccal and the apex is to
the lingual, with the canal orifice positioned at each angle
of the triangle. The cavity is entirely within the mesial
half of the tooth and need not invade the transverse ridge
but is extensive enough, buccal to lingual, to allow
positioning of instruments and filling materials. Outline
form of final preparation is identical for both a newly
erupted and an "adult" tooth. Note the orifice to the fourth
canal. Internally, the access cavity should have all orifices
positioned entirely on the pulp floor and should not extend
into an axial wall. Extension of an orifice into the axial
wall creates a mose hole effect, which indicates internal
underextension and impedes straight-line access. In such
cases the orifice must be repositioned onto the pulp floor
without interference from the axial.
3
 Mandibular molar teeth:-
A- Entrance is always gained through
the occlusal surface of all posterior
teeth. Initial penetration is made in
the exact center of the mesial pit,
with the bur directed toward the
distal. The 702U tapering fissure bur
is in an accelerated-speed contra-
angle handpiece is ideal for
perforating gold casting or virgin
enamel surface to the depth of dentin.
Amalgam fillings are penetrated with
a No.4 round bur operating in a high-
speed contra-angle handpiece.
B- According to the size of the chamber, a

regular-length No.4 or 6 round bur is
used to open into the pulp chamber.
The bur should be directed toward the
orifice of the mesiobuccal or distal
canal, where the greatest space in the
chamber exists. It will be felt to "drop"
when the pulp chamber is reached. If
the chamber is well calcifies, initial
penetration is continued until the
contra-angle handpiece rests against
the occlusal surface. This depth of 9mm is the usual
position of the floor of the chamber, which lies at the
cervical level. Working from inside out, back toward the
mesial, the bur removes enough roof of the pulp chamber
for exploration.
4
C- An endodontic explorer is used to
locate orifices of the distal,
mesiobuccal, and mesiolingual canals.
Tension of the explorer against the
walls of preparation indicates the
amount and direction of extension
necessary. Orifices of the canals form
the perimeter of preparation. Special
care must be taken to explore for an
additional canal in the distal root. The
distal canal should form a triangle with
two mesial canals. If it is asymmetric,
always look for the fourth canal 29%
of the time.
D- Again, working at slow speed from the inside to outside, a

round bur is used to remove the roof of the pulp chamber.
Internal walls and floor of preparation should not be cut
into unless difficulty is encountered in locating orifices. In
that case, surgical-length no.2 or 4 round burs are
necessary to explore the floor of the chamber.
E- Final finish and funneling of cavity walls are completed
with a 702U fissure bur or diamond point at accelerated
speed.
5
F- Final preparation provides unobstructed access to canal
orifices and should not impede the complete authority of
enlarging instruments. Improve ease of access by
"leaning" the entire preparation toward the mesial, for all
instrumentation is introduced from the mesial. Notice that
the cavity outline extends to the height of the mesial
cusps. The walls are perfectly smooth and the orifice
located at the exact pulpal-axial angle of the cavity floor.
G- "Square" outline form reflects the anatomy of the pulp

chamber. Both mesial and distal walls slope mesially. The
cavity is primarily within the mesial half of the tooth but
is extensive enough to allow
positioning of the instrument and
filling materials. The outline
form of the final preparation will
be identical for both a newly
erupted and an "adult" tooth.
Further exploration should
determine if a fourth canal can be
found in the distal root. If so, the outline is extended in
that direction. In that case, an orifice will be positioned at
each angle of the square.
Errors in cavity preparation of posterior teeth:-

1) Under extended preparation. Pulp horns have merely
been "nicked" and the entire roof of the pulp
chamber remains. "White" color dentin of the roof is
a clue to under extension.
2) Over extended preparation undermining enamel
walls. The crown is badly gouged owing to failure
to observe pulp recession in the radiograph.
3) Perforation into furca using a surgical-length bur
and failing to realize that the narrow pup chamber
had been passed. Operator error in failure to
compare the length of the bur to the depth of the
6
pulp canal floor. Length should be marked on the
bur shank with dycal.
4) Inadequate vertical preparation related to failure to

recognize severe buccal inclination of an unopposed
molar.
5) Disoriented occlusal outline form exposing only the
palatal canal. A faulty cavity has been prepared in
full crown, which was placed to "straighten" a
rotated molar. Palpating for mesiobuccal root
prominence would reveal the severity of the
rotation.
6) Perforation at the wall cavity caused by failure to
orient the bur with the long axis of the molar
severely tipped to the mesial.
7
Average length of posterior permanent teeth
Tooth Average length Canals Canals in the mesiobuccal root
Mesiobuccal 3 canals 41% One canal/one 41%

20mm foramen
Distobuccal 4 canals Two canals/one 40%
6 6 19.4mm 56.5% foramen
Palatal Two canals/two 19%
20.6mm foramina
Mesiobuccal 3 canals 54% One canal/one 63%
20mm foramen
Distobuccal Fused 46% Two canals/one 13%
7 7 19.4mm foramen
palatal Two canals/two 24%
20.8mm foramina
Mesial Two canals Mesial Distal
20.9mm 6.7%
6 6 Distal 3 canals Two canals/one One canal 71%
20.9mm 64.4% foramen 40%
4 canals 29% Two canals/two Two canals
foramina 60% 29%
Mesial Mesial Distal
7 7 20.9mm One 13% 92%
canal/one
foramen
Distal Two 49% 5%
20.8mm canals/one
foramen
Two 38% 3%
canals/two
foramina
8
9
Endodontics
Lec:7 ‫ ﺑﻠﻨﺪ ﻣﺤﻤﺪ ﺳﻠﻴﻢ‬.‫د‬
Determination of working length

Exploration for the canal orifice:-
Before the canals can be entered, their orifices must be found. In older
patients, finding a canal orifice may be the most difficult and time
consuming operation. The endodontic explorer is the greatest aid in finding
a minute canal entrance, feeling along the walls and into the floor of the
chamber in the area where the orifices are expected to be. Extension of the
walls toward these points forms the basic perimeter of the preparation.
When we find the orifices, we start to negotiate with small size instrument
ex: size 15 to be sure that the canal is patent till the apex. Start extirpation
with barbed broach, using the proper size according to the size of the canal.
The barbed broach should be loose (no engagement of dentin during
rotation).
Technique of pulp extirpation:
1-Penetrate the barbed broach along the canal wall towards the apex.
2-As it reaches to the apical constriction, move it into the center of mass of
pulp tissue
3-Rotate the broach several times in a watch winding manner to entrap the
pulp which is then withdrawn from the canal.
In case of posterior teeth, ex: mesial canal, it's so difficult to use barbed
broach, so we use a file instead of barbed broach.
The determination of an accurate working length is one of the most critical
steps of Endodontic therapy. The cleaning, shaping and obturation of the
root canal system cannot be accomplished accurately unless the working
length is determined precisely.
Anatomic consideration and terminology:-

 Working length: - the distance from a coronal reference point to the
point of which canal preparation and obturation should terminate, the
ideal apical reference point in the canal, the "apical stop", so to
speak.
 Anatomic apex: - is the tip or the end of the root determined
morphologically, whereas the radiographic apex is the tip or end of
the root determined radiographically. Root morphology and
radiographic distortion may cause the location of the radiographic
apex to vary from the anatomic apex.
1
 Apical foramen: - is the main apical opening of the root canal. It's
frequently eccentrically located away from the anatomic or
radiographic apex.
 Apical constriction:- is the apical
portion of the root canal having the
narrowest diameter. This position
may vary but is usually 0.5 to 1.0
mm short of the center of the apical
foramen.
 Cementodentinal junction:- is the
region where the dentin and
cementum are united, the point of
which the cemental surface
terminates at or near the apex of the
tooth. It must be pointed out,
however, that the cementodentinal
junction is a histologic landmark that cannot be located clinically or
radiographically.
Methods of determining working length:-

 Ideal method:-
To achieve the highest degree of accuracy in working length
determination, a combination of several methods should be used. This is
most important in canals for which working length determination is
difficult. The most common methods are radiographic methods, digital
tactile sense, and electronic methods.
1-Radiographic methods:-
Radiographic method known as the Ingle method has been compared
with three other methods of determining working length. The Ingle method
proved to be superior to others in the study. It showed a high percentage of
success with a smaller variability. This method, first proposed more than 40
years ago, has withstood the test of time and has become the standard as the
most commonly used method of radiographic working length estimation.
Radiographic Apex Location:-
The following items are essential to perform this procedure:-
1) Good, undistorted, preoperative radiographs showing the total length
and all roots of the involved tooth.
2) Adequate coronal access to all canals.
3) An endodontic millimeter ruler.
4) Working knowledge of the average length of
all teeth.
5) A definite, repeatable plane of reference to an
anatomic landmark on the tooth, a fact that
should be noted on the patient's record.
2
Reference point:- is the site on the occlusal or incisal surface from
which measurements are made. This point
is used through out canal preparation and
obturation. A reference point that will
easily visualize during preparation is
chosen. Usually this is the highest point on
the incisal edge on the anterior teeth and a
buccal cusp tip on posterior teeth.
It is imperative that teeth with fractured
cusps or cusps severely weakened by caries or restoration be reduced to
a flattened surface, supported by dentin. Failure to do so
may result in cusps or weak enamel walls being
fractured between appointments. Thus, the original site
of reference is lost. If this fracture goes unobserved,
there is the probability of over instrumentation and
overfilling, particularly when anesthesia is used. To
establish the length of the tooth, a stainless steel reamer
or file with an instrument stop on the shaft is needed.
The exploring instrument size must be small enough to
negotiate the total length of the canal but
large enough not to be loose in the canal.
A loose instrument may move in or out of
the canal after the radiograph and cause
serious error in determining the length of
tooth.
Method:-
1- Measure the tooth on the preoperative radiograph (initial
measurement).
2- Subtract at least 1.0 mm "safety allowance" for possible image
distortion or magnification.
3- Set the endodontic ruler at this tentative working length and
adjust the stop on the instrument at that level.
4- Place the instrument in the canal until the stop is at the plane
of reference unless pain is felt, in which case, the instrument is
felt at level and the rubber stop readjusted to this new point of
reference.
5- Expose, develop, and clear the radiograph.
6- On the radiograph, measure the difference between the end of
the instrument and the end of the root and add this amount to
the original measured length the instrument extended into the
tooth. If, through some oversight, the exploring instrument has
gone beyond the apex, subtract this difference.
3
7- From this adjusted length of tooth, subtract a 1.0 mm "safety
factor" to conform to the apical termination of the root canal at
the apical constriction.
If, radiographically, there is no resorption of the root end or bone,
shorten the length by
the standard 1.0mm.
If periapical bone
resorption is
apparent, shorten by
1.5mm, and if both
root and bone
resorption is
apparent, shorten by
2.0 mm. The reasoning behind this suggestion is thoughtful. If there
is root resorption, the apical constriction is probably destroyed,
hence the shorter move backup the canal. Also, when bone
resorption is apparent, there probably is also root resorption, even
though it may not be apparent radiographically.
8- Set the endodontic ruler at this new corrected length and
readjust the stop on the exploring instrument.
2-Digital Tactile Sense:-

If the coronal portion of the canal is not constricted, an experienced
clinician may detect an increase in resistance as the file approaches the
apical 2 to 3mm. This detection is by tactile sense. In this region, the canal
frequently constricts before exiting the root. There is also a tendency for
the canal to deviate from the radiographic apex in this region.
The accuracy of just 64% using digital tactile sense. Another study found
that the exact position of the apical constriction could be located accurately
by tactile sense in only 25% of canals in their study.
All clinicians should by aware that this method, by itself, is often inexact. It
is ineffective in root canals with an immature apex and is highly inaccurate
if the canal is constricted throughout its entire length or if the canal has
excessive curvature. This method should be considered supplementary to
high-quality, carefully aligned, parallel, working length radiographs and/or
an apex locator.
A survey found that few general practice dentists and no endodontists trust
the digital tactile method of determining working length by itself. Even the
most experienced specialist would be prudent to use two or more methods
to determine accurate working lengths in every canal.
3-Determination of Working Length by Electronics:-

Electronic devices have been designed to determine canal length by
“reading” when vital tissue has been reached by the file tip at the apical
foramen. The electronic principle is relatively simple and is based on
4
electrical resistance. In 1918, Custer was the first to report the use of
electric current to determine working length. The research on dogs using
direct current discovered that the electrical resistance between the
periodontal ligament and the oral mucosa was a constant value of 6.5 Kilo-
ohms. They used a simple direct current ohmmeter to measure a constant
resistance of 6.5 kilo-ohms between oral mucous membrane and the
periodontium regardless of the size or shape of the teeth. The device used
became the basis for most apex locators. The principle is based on the
electrical resistance of different tissues. When the circuit is
complete, resistance decreases and current begins to flow.
All apex locators function by using the human body to complete an
electrical circuit. One side of the apex
locator's circuitry is connected to an
endodontic instrument. The other side is
connected to the patient's body, either by
a contact to the patient's lip or by an
electrode held in the patient's hand. The
electrical circuit is complete when the
endodontic instrument is advanced
apically inside the root canal until it
touches periodontal tissue. The display on the apex locator indicates that
the apical area has been reached. According to the device, this event is
signaled by a beep, a buzz, flashing light, digital readouts, or a pointer on a
dial.
Old types were affected by the presence of saliva, blood inside the canal
while recent types are not affected by them and work efficiently in their
presence. As recent types depend on the electrical impedance which is the
different electric resistance between the cervical and apical dentin.
Uses of apex locators:

1-They are useful in conditions where apical portion of canal system is
obstructed by:
a-impacted teeth, b-zygomatic arch, c-excessive bone density, d-tori, e-
overlapping roots, f-shallow palatal vault.
In such cases, they can provide information which radiographs cannot.
2-They are useful in patient who cannot tolerate X-ray film placement
because of gag reflex.
3-In case of pregnant patients, to reduce the radiation exposure, they can be
valuable tool.
4-They can also be used in children who may not tolerate taking
radiographs, disabled patients and patients who are heavily sedated.
5-They are helpful in root canal treatment of teeth with incomplete root
formation, requiring apexification and to determine working length in
primary tooth.
5
Contraindications:-
The use of apex locators and other electrical devices such as pulp
testers, electrosurgical instruments and desensitizing equipment, is
contraindicated for patients who have cardiac pacemakers. Electrical
stimulation to the pacemaker patient can interfere with pacemaker function.
The severity of the interference depends on the specific type of pacemaker
and the patient's dependence on it. In special cases, an apex locator may be
used on a patient with a pacemaker when it's done in close consultation
with the patient's cardiologist.
Thank you
6
Endodontics
Lec.8 Dr.Iman Mohammed
‫د ﺑﻠﻧد ﻣﺣﻣد ﺳﻠﻳﻡ‬
Preparation of the root canal system

Root canal therapy may be defined as the complete removal of the
irreversibly damaged pulp followed by thorough cleaning, shaping and
obturation of the root canal system so that the tooth may remain as a
functional unit within the dental arch.
Objectives of root canal preparation:-

1-The root canal preparation should develop a continuously
tapering cone: this shape mimics the natural canal shape.
2-Making the preparation in multiple planes which introduces
the concept of flow: this objective preserves the natural curve of
the canal.
3-Making the canal narrower
apically and widest coronally:
to create a continuous taper
up to apical third which
creates the resistance form to
hold gutta-percha in the
canal.
4- Avoid transportation of the
foramen: there should be
gentle and minute enlargement of the foramen while
maintaining its position.
5-Keep the apical opening as small as possible: the foramen size
should be kept as small as possible as overlapping of foramen
contributes to number of iatrogenic problems.
1
Methods for using reamers and files:-
Some confusion exists as to the actions for using enlarging
instruments and the instruments themselves.
Reaming:-
Reaming involves placement of the instrument
toward the apex until some binding is felt and then
turning the handle more than a full revolution.
Clockwise turning will remove material from the canal
by way of the flutes revolution, whereas
counterclockwise turning will force material apically.
The major effectiveness of hard tissue removal by
reaming is in the insertion of the instrument by shaving
the dentin walls.
Filing:-
Filing involves placement of the instrument toward
the apex until some binding is felt and then removing the
instrument by scraping against a side of the dentin wall
with little or no revolution of the handle. This dragging
against the side of the wall is also referred to as rasping
action. The major effectiveness of hard tissue removal by
filing is in the outstroke or withdrawal of the instrument by
dragging the flutes on the dentin walls.
Watch winding
It is back and forth oscillation of endodontic instrument
(file or reamer) right and left as it is advance into the canal.
The angle of rotation is usually 30 to 60 degrees.
Circumferential filing:-
Circumferential filing is a method of filing whereby
the instrument is moved first toward the buccal (or the labial) side of the
canal, then reinserted, and removed slightly mesially. This continues around
the preparation to the lingual aspect her then to the distal until all the dentin
walls have received planing. This technique enhances preparation when a
flaring method is used by widening the orifice of the canal considerably,
whereas the apical portion is kept relatively small.
2
Most roots are oval in cross
section and are wider buccolingually
than mesiodistally. If such a root
contains only one canal, which many
but not all do, it will be wider
buccolingually as well. In these cases
the circumferential filing is
emphasized in the buccolingual
direction. The oval canal is made into
a wider and larger oval. This permits easier placement of precurved
instruments, gutta-percha cones, and finger spreaders. Such a preparation is
developed solely and specifically for gutta-percha canal filling rather than
silver points.
Root canal configuration:-

The shapes of the root canals are divided into:-
Type I A single canal exist or leaving the pulp chamber which continue
as a single canal to the apex of the root to open in a single apical
foramen.
Type II Two canals leaving the pulp chamber, then meet and join each
other at eh apical third to be opened in a single apical foramen.
Type III Two canals leaving pulp chamber and continue as two separated
canals to be opened in the root apex into two separated apical
foramenae.
Type IV Single canal leaving the pulp chamber which when reach the
apical third, bifurcate into two canals and open into two
separated apical foramenae.
3
Canal enlargement procedures:-
The principles of root canal preparation are to remove all organic
debris and microorganisms and to shape the walls of the root canal so that
the entire root canal space may be obturated. Currently, the root canal filling
material of choice is gutta-percha, which requires a gradual even funnel-
shaped preparation with the widest part coronally and the narrowest part 1.0
mm short of the root apex.
Wide, relatively straight canals are simple to prepare, but fine curved
canals can present considerable difficulties. A number of techniques have
been described, all of which have been designed to produce a tapered
preparation.
 The standardized procedure (conventional technique):-

This technique was used for many years and requires each instrument,
file or reamer, to be placed to the full working length. The canal was
enlarged until clean white dentin shaving were seen on the
apical few millimeters of the instrument. The filing was
continued for a further 2 or 3 sizes, to complete the
preparation. This method was satisfactory in straight
canals, but was quite unsuitable for curved canals. As the
instrument sizes increase, they become less flexible and
cause errors in curved root canals. The common problems
are ledging, zipping, elbow formation, perforation and
loss of working length owing to impaction of dentin
debris.
 Flaring technique:-
The apical portion of the canal is enlarged to a specific degree and then the
remainder of the canal is enlarged to even wider sizes to attain an
exaggerated funnel shape.
The flared preparation has several physical advantages:-
1- The smaller, more flexible files are used in apical portion, and the
stiffer files need not be forced but are used short of the apex.
2- More apical dentin is available for the dentin matrix, thus if initial
files are slightly too long, some dentin can retain gutta-percha within
the canal.
3- In curved canals, files often bind in the coronal portion and then
become ineffective at the apex. With the coronal portion larger, files
are more effective and may retain original canal shape better.
4
4- Because the canal is much wider, the intracanal irrigant have more
room to gain access to the irritants and necrotic debris.
5- The wider coronal portion allows for easier placement for finger
spreaders and gutta-percha cones.
6- The desired shape of the canal preparation is obtained, as narrow as
possible at the apex consistent with cleaning the canal and as wide as
possible at the orifice consistent with not gutting the crown.
Step-back technique:-
Basically this technique involves the canal preparation into two phases;
phase I involves the preparation of apical constriction and phase II involves
the preparation of the remaining canal
In this technique, we usually prepare the apical part with flexible
instruments (i.e. small sizes, 10, 15, 20, 25, 30), but sizes beyond size 30 are
considered as a non-flexible instruments.
The first step in this technique is the selection and determination of initial
size of instrument according to width of apical third.
Initial size: - is the first instrument, which is inserted inside the canal and
goes to the full length and has slight engagement to the
walls. Suppose, we had a tooth with initial size 25 file, and
working length 20mm…
→File 25 W.L. = 20mm (initial size).
→File 30 W.L. = 20 mm→ irrigation.
→File 35 W.L. = 20 mm → irrigation.
→File 40 W.L. = 20 mm → (master apical file).
Master apical file:- is the widest instrument that goes to
established working length.
→File 40 W.L. = 20 mm (recapitulation).
5
Recapitulation: - is to ensure that the canal is remained patent.
Note: - due to continuous instrumentation with size 40 file, the file becomes
loss inside the canal, so, we select the next larger size (45) as a MAF.
Step down technique (Crown down technique):-

The pulp chamber is first copiously irrigated with irrigant
solution. Then, start exploration of the canal with a fine, stainless
steel file (No. 0.8, 10, 15, and 20 file). It’s important that the canal
be patent to the apical constriction before cleaning and shaping
begin.
Gates-Glidden burs are next introduced into the canal,
beginning with a size 2 and followed by a size 3. The No. 2 bur is
inserted 14-16 mm into the canal from the occlusal reference point.
The No.3 bur is placed 11-13 mm into the canal and is directed
apically and laterally away from the furcation. Gates-Glidden burs
should be rotated with constant medium drill speed form the time
they enter the canal until removed. If a bur does break, it usually
does so near the hand piece head and may be retrieved easily form
the tooth instrumentation with the step-down technique in the
radicular access is accomplished using only light pressure directed
apically. Preparation of the apical part of the canal is achieved
6
using the step back technique. The instrument should be precurved
and only a push-pull motion is used, moving the file clockwise
circumferentially. No turning motion is used.
Starting with a file size 20 at the working length, and
progressing to sizes 25 and 30, an apical stop is made. Copious
irrigation and recapitulation will prevent build up of canal debris.
The master apical file (MAF) size is usually 30; larger

instruments will start to produce ledging or zipping.
After that we use the step back technique to complete the apical
third preparation.
Advantage of step down technique:-

1) Most of the microorganisms will be in the coronal third of the
root canal system; early removal of these will reduce the
possibility of their inoculation into the apical portion of the
canal and thence into the periradicular tissues. In addition,
hydrostatic pressure can occur within the root canal if
working length confirmation or apical preparation is initiated
at the start of preparation because the file will act like a
piston in a cylinder. This pressure may force pulp debris,
dentin chips, irrigant solution and microorganisms through
the apical foramen. Extrusion of material is greater when the
instrument size is approximately the same as that of the
apical section of the root canal.
7
2) Early flaring of the coronal part of the canal system prevents
binding of the instruments as they are unencumbered through
out most of their length and also gives better access to the
apical part of the root canal.
3) If removal of interferences at the base of the pulp chamber
and in the coronal part of the root canal is undertaken prior to
working length determination, the latter is less likely to alter
during preparation.
4) Early coronal flaring allows better penetration of the irrigant
solution.
Balanced force technique:-

The technique can be described as “positioning and pre-
loading an instrument through a clockwise rotation and then
shaping the canal with a counter clockwise rotation”.
For the best results, preparation is completed in a step-down

approach. The coronal and mid thirds of a canal are flared with
Gates-Glidden drills, and then instrument shaping is carried into
the apical areas. This approach is less difficult than the
conventional step-back technique. Increasing the diameter of the
coronal and mid-thirds of a canal removes most of the
contamination and provides access for a more passive movement
of hand instruments into the apical third. After mechanical shaping
with Gates-Glidden drills, balanced force hand instrumentation
begins, placing, cutting and removing instruments using only
8
rotary motions. Insertion is done with a quarter-turn (90˚)
clockwise rotation while slight apical pressure is applied. Cutting
is accomplished by making a counter-clockwise rotation. The
amount of apical pressure must be adjusted to match the file size
(i.e. very light for fine instruments to fairly heavy for large
instruments). Pressure should maintain the instrument at or near its
clockwise insertion depth. Then counter clockwise rotation and
apical pressure act together to enlarge and shape the canal to the
diameter of the instrument. Counter clockwise motion must be
120˚ or greater. It must rotate the instrument sufficiently to remove
the next larger cutting edge into the location of the blade that
preceded it, in order to shape the full circumference of a canal. A
greater degree of rotation is preferred and will more completely
shape the canal to provide a diameter equal to or greater than that
established by the counterclockwise instrument twisting during
manufacture.
Repeating the previously described steps gradually enlarges the

apical third of the canal by advancing to larger and larger
instruments.
9
Endodontics
Lec:9
Irrigants and chelating agents
Functions of irrigants:-
Irrigants perform important physical and biologic functions during
endodontic therapy. Their action is unquestionably more significant than
that supplied by the use of intra-canal medicaments. When there is a wet
environment during canal preparation, the
dentin shavings are floated to the chamber,
where they may be removed by aspiration or
paper points. Therefore, they do not pack near
the apex to prevent proper canal filling. Files
and reamers are much less likely to break
when the canal walls are lubricated by the
irrigants.
Many liquids would provide these aids,
but in addition, the irrigants that are typically
used have the function of being necrotic tissue
solvents. When used with canal
instrumentation, the irrigants loosen debris,
pulp tissue, and microorganisms from the
irregular dentin walls so that they can be removed from the canal.
Because reamers and files are much too small to fit into accessory canals,
it is the solvents' action that removes the tissue remaining there so that the
subsequently used filling materials may be packed or pushed into these
areas.
Most irrigants are germicidal but have further antibacterial effect
by ridding the canal of the necrotic debris. With reduced substrate
present, the microorganisms have less chance for survival. Irrigants also
have a bleaching action to lighten teeth discolored by trauma or extensive
silver amalgam restorations and decrease the chance of postoperative
darkening.
The commonly used irrigants are capable of causing inflammation
of periapical tissue. Therefore, instrumentation must be confined within
the canal to limit the forcing of irrigants through the apical foramen.
Unquestionably, solution frequently does reach the periapical tissue and
some inflammation results. Since the stronger solvents produce greater
1
inflammatory response, the strength of the solutions should be kept to the
lowest level that will be effective in debridement.
Useful Irrigants:-
Sodium hypochlorite (NaOCl), is the most widely used irrigant in
endodontics and has effectively aided canal preparation procedures for
many years. NaOCl is a clear, pale green yellow liquid with strong odor
of chlorine. It is easily miscible with water and gets decomposed by light.
A 5% solution provides excellent solvent action but is dilute enough to
cause only mild irritation when contacting periapical tissue. Household
liquid bleach (Clorox, Linco) has 5.25% NaOCl and therefore requires
slight addition of distilled water to lower the incidence of periapical
inflammation. It is an excellent antibacterial agent, capable of dissolving
necrotic tissue, vital pulp tissue, and the organic components of dentin
and biofilms. NaOCl solution, commonly known as bleach, is frequently
used as a disinfectant or a bleaching agent. It is the irrigant of choice in
endodontics, owing to its efficacy against pathogenic organisms and pulp
digestion, and satisfies most of the preferred characteristics stated earlier.
Hydrogen peroxide solution (H2O2), USP, is also widely used in

endodontics, with two modes of action. The bubbling of the solution
when in contact with tissue and certain chemicals physically foams debris
from the canal. In addition, the liberation of oxygen destroys strictly
anaerobic microorganisms. It is clear odorless liquid. It is mainly the 3
percent solution, which is used as an irrigating agent.
The solvent action of H2O2 is much less
than that of NaOCl. However, many clinicians use
the solutions alternately during treatment. This
method is strongly suggested for irrigating canals
of teeth that have been left open for drainage,
since the effervescence is effective in dislodging
food particles as well as other debris that may
have packed the canal.
Carbamide peroxide: is available in any anhydrous glycerol base (Gly-

Oxide) to prevent decomposition and is a useful irrigant. It is better
tolerated by periapical tissue than NaOCl yet has greater solvent action
and is more germicidal than H2O2. Therefore, it is an excellent irrigant for
treating canals with normal periapical tissue and wide apices, in which
the more irritating solutions would cause severe inflammation when
forced out of the canal. The best use for Gly-Oxide is in narrow and/or
2
curved canals, utilizing the slippery effect of the glycerol. Whereas
chelating agents react with dentin and may cause root perforation or
ledging in softened walls, this action will not occur with Gly-Oxide,
where only lubrication is enhanced. Because the canal walls are slippery,
they are easier to prepare but are less likely to be gouged or perforated.
Chlorhexidine: It is a potent antiseptic, which is widely used for

chemical plaque control in the oral cavity in concentration of 0.2 percent
while 2 percent is the concentration used for irrigating root canal. CHX
is a wide-spectrum antimicrobial agent, active against gram-positive and
gram-negative bacteria as well as yeasts. Owing to its cationic nature,
CHX is capable of electrostatically binding to the negatively charged
surfaces of bacteria, damaging the outer layers of the cell wall and
rendering it permeable. CHX is a strongly basic molecule and is stable as
a salt. CHX digluconate salt is easily soluble in water. CHX does not
possess some of the undesired characteristics of sodium hypochlorite (ie,
bad smell and strong irritation to periapical tissues). However, CHX has
no tissue-dissolving capability and therefore it cannot replace sodium
hypochlorite.
The popularity of CHX is its substantivity (ie, continued antimicrobial
effect), because CHX binds to hard tissue and remains antimicrobial.
However, similar to other endodontic disinfecting agents, the activity of
CHX depends on the pH and is also greatly reduced in the presence of
organic matter.
Saline:
We use it since it is not irritant to the P.A. tissue area; it has no solvent
action just flushing to the canals wall.
Irigation devices and method:
The effectiveness and safety of irrigation depends on the means of

delivery. Traditionally, irrigation has been performed with a plastic
syringe and an open-ended needle into the canal
space. An increasing number of novel needle-
tip designs and equipment are emerging in an
effort to better address the challenges of
irrigation.
Syringes:
Plastic syringes of different sizes (1–20 mL) are
most commonly used for irrigation. Although
3
large-volume syringes potentially allow some time-savings, they are more
difficult to control for pressure and accidents may happen. Therefore, to
maximize safety and control, use of 1- to 5-mL syringes is recommended
instead of the larger ones. Because of the chemical reactions between
many irrigants, separate syringes should be used for each solution.
Needles:
Although 25-gauge needles were commonplace for endodontic irrigation
a few years ago, they were first replaced
by 27-G needles, now 30-G and even
31-G needles are taking over for routine
use in irrigation. As 27 G corresponds to
International Standards Organization
size 0.42 and 30 G to size 0.31, smaller
needle sizes are preferred.
Several studies have shown that the
irrigant has only a limited effect beyond
the tip of the needle because of the
dead-water zone or sometimes air
bubbles in the apical root canal, which
prevent apical penetration of the
solution. However, although the smaller needles allow delivery of the
irrigant close to the apex, this is not without safety concerns. Several
modifications of the needle-tip design have been introduced in recent
years to facilitate effectiveness and minimize safety risks.
A bend of approximately 30
degrees is made in the center of
the needle so the canals of both
anterior and posterior teeth are
reachable.
Irrigants must never be forcibly inserted into the
periapical tissue but gently placed within the canal. It
is the action of the intracanal instruments that
distributes the irrigant to the nooks and crannies of
the canal rather than the injection syringe. For
relatively large canals the tip of the syringe is placed
until resistance from the canal walls is felt, then the
tip is withdrawn a few millimeters. The solution was
expressed very slowly until much of the chamber is
filled. In the treatment of posterior teeth and/or small
canals, the solution was deposited in the chamber. The files will carry the
irrigant into the canal, and the capillary action of the narrow canal
4
diameter will retain much of the solution. Excess
irrigant is carried away by aspiration with a small tip, of
approximately 16 gauge, if available. Otherwise, a
folded gauze pad (2 X 2 inches) is held near the tooth to
absorb the excess. To dry a canal in a case where
aspiration is not available, the plunger of the irrigating
syringe may be withdrawn, and the bulk of the solution will be aspirated
in that manner. Paper points are then used to remove residual liquid.
EndoActivator:
EndoActivator is a new type of irrigation
facilitator. It is based on sonic vibration
(up to 10,000 cpm) of a plastic tip in the
root canal. The system has 3 different
sizes of tips that are easily attached (snap-
on) to the handpiece that creates the sonic
vibrations. EndoActivator does not deliver
new irrigant to
the canal but it
facilitates the penetration and renewal of the
irrigant in the canal. Two recent studies have
indicated that the use of EndoActivator
facilitates irrigant penetration and mechanical
cleansing compared with needle irrigation, with
no increase in the risk of irrigant extrusion
through the apex.
EndoVac:
EndoVac represents a novel

approach to irrigation as, instead
of delivering the irrigant
through the needle, the
EndoVac system is based on a
negative-pressure approach
whereby the irrigant placed in
the pulp
chamber is sucked down the root canal
and back up again through a thin needle
with a special design. There is evidence
that, compared with traditional needle
irrigation and some other systems, the
EndoVac system lowers the risks
5
associated with irrigation close to the apical foramen considerably.
Another advantage of the reversed flow of irrigants may be good apical
cleaning at the 1-mm level and a strong antibacterial effect when
hypochlorite is used, as shown by recent studies.
chelating agents:
Complete cleaning of the root-canal system requires the use of irrigants
that dissolve organic and inorganic material. As hypochlorite is active
only against the former, other substances must be used to complete the
removal of the smear layer and dentin debris. EDTA effectively dissolve
inorganic material, including hydroxyapatite. They have little or no effect
on organic tissue and alone they do not have antibacterial activity.
The problems of enlarging very sclerotic canals nagged even the earliest
practitioners in endodontics. Chelating agents act on calcified tissues only
and have little effect on periapical tissue. Their action is to substitute
sodium ions, which combine with the dentin to give soluble salts, for the
calcium ions that are bound in less soluble combination. The edges of the
canal are thus softer, and canal enlargement is facilitated.
Chelating agents are placed in the orifice of a canal to be enlarged
on the tip of the endodontic explorer or on the flutes of the enlarging
instrument if the agent is foamy (as is RC-Prep) or by plastic irrigating
syringe if liquid (e.g., EDTA). EDTA reacts with glass, so syringes of
that material may not be used.
Chelating agents may be useful in the location of a difficult-to-find
orifice by sealing in the chamber between appointments. Because the
orifices are less calcified than the surrounding dentin, sufficient softening
may allow it to be located with the sharp tip of the endodontic explorer at
the next appointment.
If misused, chelating agents may cause problems during
endodontic therapy. They should not be used in a ledged or blocked canal
to aid in reaching the apex. If a sharp instrument is forced or rotated
against a wall softened by the chelate, a new but false canal will be
started. The operator may erroneously believe that the canal has been
located and continue the preparation, thus losing any chance for finding
the true canal.
Chelating agents are dangerous in curved canals once the larger-
sized instruments (size 30 or greater) are being used. These instruments
are not as flexible as the smaller sizes and, with the canal walls softened,
may produce an elliptication of the apex or root perforation.
The best use of these agents is to aid and simplify preparation for
very sclerotic canals after the apex has already been reached with a fine
instrument.
6
EDTA…
Patterson did much research on the disodium salt of ethylene-
diamine tetra acitic acid (EDTA).
EDTA will remain active within the canal for 5 days if not
inactivated. If the apical constriction has been opened, the chelate may
seep out into the tissue and damage the periapical bone. For this reason,
at the completion of the
appointment the canal must be
irrigated with a sodium
hypochlorite-containing
solution, a small file being
placed into each canal where
EDTA was used to ensure penetration of the inactivator.
Some research seems to indicate that the use of EDTA in canal
preparation aids in the removal of the smear layer on the dentin wall. This
might allow for better surface contact between the canal filling and the
dentin wall and better potential penetration of the sealer into the dentinal
tubules. EDTA manufactured as liquids and gels. EDTA used as a 17%
neutralized solution
EDTAC…
The addition of Cetavlon, a quaternary ammonium compound, to
EDTA produces a solution called EDTAC, which has greater germicidal
activity. However, it has greater inflammatory potential to tissue as well.
The inactivator for EDTAC is NaOCl.
RC-Prep…
As developed by Stewart, RC-Prep combines the
functions of EDTA plus urea peroxide to provide both
chelation and irrigation. The foamy solution has a natural
effervescence that is increased by irrigation with NaOCl
to aid in the removal of debris. RC-Prep may be placed
in the canal on the flutes of a file by plastic irrigating
syringe.
7
Endodontics
Lec:10
Intracanal medicaments
Originally, endodontics was mainly a therapeutic procedure in
which drugs were used to destroy microorganisms, fix or mummify vital
tissue, and effect a sealing of the root canal space. The drugs used were
generally caustic, such as phenol and its derivatives, and periapical
tissues were frequently adversely affected.
Gradually the reliance on drugs has been replaced by emphasis on
debridement. It cannot be argued that what is removed from the canal has
a greater significance in endodontic success than what is placed in the
canal. Even so, drugs are still used as intra treatment dressings, although
an ever increasing number of endodontists use them only for symptomatic
cases.
Functions of intracanal medicaments:
1. They disinfect the root canal system.
2. To reduce the number of microorganism and prevent the growth of any
new microorganism.
3. Rendering contents of canal inert.
4. Prevention or control of post treatment plan.
5. Control of persistent periapical abscess in weeping canal.
Phenol and related volatile compounds…

Phenol was used for many years for its disinfectant and caustic
action. However, because it has strongly inflammatory potential, at
present it is rarely used as an intracanal medicament.
Eugenol also has been used in endodontics for many years. It is a
constituent of most root canal sealers and is used as a part of many
temporary sealing agents. Although the compound has high irritating
potential when evaluated histologically, it seems to be extremely soothing
clinically to vital tissue, probably from some type of caustic action to
irritated nerve endings. It is used as an intracanal medicament after partial
or complete pulpectomy.
Camphorated monoparachlorophenol (CMCP) This consists of
2 parts of parachloro phenol and 3 parts of gum camphor, is probably the
most widely used medicament in endodontics presently, even though its
use has decreased considerably in the past few years. It has a wide
antibacterial spectrum and is effective against fungi as well. CMCP is
much less irritating to periapical tissue than either phenol or eugenol
without sacrificing antimicrobial action. It is inexpensive, has a long shelf
life, and does not appear to yield false-negative cultures if carried to the
medium on a paper point. It is placed on a cotton pellet in the pulp
chamber of a tooth in treatment and the vapors will penetrate the entire
canal preparation.
Formocresol, a combination of formalin and cresol, is used as a
dressing for pulpotomy to fix the retained pulpal tissue. It may also be
used as an intratreatment medicament when a pulpotomy is performed as
emergency treatment to relieve pain, in situations where pulp
inflammation is confined to the pulp chamber.
PBSC…
As mentioned by Grossman, PBSC has enjoyed wide use among
dentists trained at eh University of Pennsylvania and those who have
participated in postgraduate courses at that institution. The constituents of
the paste are as follows:
Penicillin: Effective against gram-positive microorganisms.

Bacitracin: Effective against penicillin-resistant microorganisms.
Streptomycin: Effective against the gram-negative microorganisms.
Caprylate: As the sodium salt, effective against fungi.
Nystatin replaces sodium caprylate as the antifungal agent in a

similar medicament, PBSN. Both are available in a paste form that may
be injected into root canals or impregnated on paper points. Because there
is no volatility, the drug must be placed in the canal to have effect in that
area.
Sulfonamides…
Sulfanilamide and sulfathiazole are used as medicaments by
mixing with sterile distilled water or by placing a moistened paper point
into a fluffed jar containing the powder. Yellowish tooth discoloration
has been reported after use. The medication is suggested for use when
closing teeth that had been left open after an acute periapical abscess.
Corticosteroid-antibiotic combinations…
Medications that combine antibiotic and corticosteroid elements
are highly effective in the treatment of over instrumentation; they must
be placed into the inflamed periapical tissue by a paper point or reamer to
be effective.
The corticosteroid constituent reduces the periapical inflammation
and gives almost instant relief of pain to the patient who has complained
of extreme tenderness to percussion after canal instrumentation. The
antibiotic constituents are present so that no overgrowth of
microorganisms will occur with the inflammatory response diminished.
Calcium hydroxide as a medicament for "weeping" cases…

One of the most perplexing conditions to treat is the tooth with
constant clear or reddish exudation associated with a large apical
radiolucency. The tooth often is asymptomatic, but it may be tender to
percussion or sensitive to digital pressure over the apex. If cultured, the
drainage generally will not support bacterial growth. When opened at the
start of the endodontic appointment, a reddish discharge may well up,
whereas at a succeeding appointment the exudates will be clear. Some
pressure is present, but not nearly as much as with an acute periapical
abscess. If the tooth is left open under a rubber dam for 15 to 30 minutes,
it may be closed up by absorbing the exudates with an aspirator and paper
points; however, a similar condition will still be present at the next
appointment. The canal has already been enlarged to a more than
acceptable size. This is referred to as a weeping canal.
The exact mechanism for the action of calcium hydroxide in this
type of case is an object of much conjecture. I believe that it is closely
related to the pH of the periapical tissues, which must be acidic in the
weeping stage. The pH is converted by the paste to a more basic
environment. Others believe that the calcifying potential of the
medicament starts to build up bone in the lesion. Still others suggest that
the caustic action of the calcium hydroxide burns residual chronic
inflamed tissue. Repair of periapical tissues after RCT of teeth periapical
lesions was better when Calcium hydroxide was used an ICM or dressing
before obturation. Merio Tanomarn.
In cases of apical periodontitis, root canals dressing with Calcium
hydroxide produce definite signs of healing after only few days. Calcium
hydroxide can be used as a powder with various vehicles such as water,
saline, etc.
Endoseptone
It is composed of p-Chlorophenol 30 %, Thymol 5 %, Dexamethasone
Acetate 0.1 %, is a solution which offers a triple-action: bactericidal,
sedative and anti-inflammatory. It also reduces the risk of allergic
reactions.
Indications:
 Disinfection of the root canal and deep caries
 Treatment against gangrene of the pulp
 Disinfection of narrow, obturated or partially calcified root canals
Directions for use:
1-Dry the root canal thoroughly
2-Following a pulpectomy insert 1 or 2 drops of the preparation into the
root canal and allow a few minutes for it to take effect. Remove any
excess solution with a cotton pellet or a gauze.
3-Following the extraction of gangrenous pulp use as a dressing by
inserting into the root canal. Leave « in situ » for at least 3 days. Make
sure the canal is completely disinfected after that period. If this is not the
case, repeat the dressing before the final obturation.
Chlorhexidine as irrigants and intracanal medicaments:
Chlorhexidine (CHX) is a broad-spectrum antimicrobial agent effective

against gram-positive and gram-negative bacteria. It has cationic
molecular component that attaches to negatively charged cell membrane
areas, causing cell membrane lyses. CHX has been used in periodontal
therapy for many years. Its use as an endodontic irrigant is based on it is
substantively long lasting antimicrobial effect.
Recently Chlorhexidine available as gutta-percha point (activ point) for
temporary root canal filling and for emergency root canal treatment.
Activ point consists of chlorhexidine diacetate(5%), gutta-percha, ZnO,
BaSO4, and coloring agents. Normally, activ point remains in the canal
for 1-3 weeks, but in specific clinical cases, it should be replaced every 2-
3 days.
Sealing agents for inter-treatment dressings:-

Need for sealing agents
Because Endodontic treatment usually takes two or more appointments,
some type of temporary sealing agent needed to close the access cavity
between visits. The material selected must provide for effective closure
against microorganisms and salivary contamination, which would bring
irritants to the periapical tissue if allowed free passage. The access-
sealing agent must also retain the intracanal medicament, if used, within
the tooth to allow effectiveness for the drug.
Types of available sealing agents:

According to radioisotope studies, silver amalgam plus cavity
varnish is the most effective sealant available in dentistry. Unfortunately,
it would be difficult and time consuming to use those materials at the
conclusion of each appointment and then have to drill everything out at
the next visit.
Fortunately, zinc oxide powder with eugenol (ZOE) provides an
excellent seal and is much easier to place and remove than amalgam. The
addition of zinc acetate crystals speeds the set of ZOE without decreasing
the sealing properties.
Cavit was introduces for use in Endodontics. Both are easy to
apply, and Cavit may be removed with a spoon excavator, not even
requiring a bur.
Recently a light-cured material, TERM (Temporary Endodontic
Restorative Material), has been introduced. Its major advantages are the
ease with which it may be used, since it may be placed with a syringe
from sterile prepacked compules, and it is set by exposure to visible light
for 20 seconds.
Endodontics
Lec:11
Engine – Driven Instruments

Engine-driven instruments can be used in three types of contra-
angle handpieces:
1-A full rotary handpiece, either latch or friction gripe.
2-A reciprocating /quarter-turn handpiece.
3-A special handpiece that imparts a vertical stroke but with an
added reciprocating quarter-turn that "cut in" when the
instrument is stressed.
Rotary Contra-Angle Handpiece Instruments:-

Instrumentation with a full rotary handpiece is by straight-line
drilling or side cutting. Mounted with round or tapered burs or
diamond points, full rotary contra-angle handpiece can be used to
develop coronal access to canal orifices.
Since some of these instruments
(stainless) do not readily bend, they should
be used in perfectly straight canals. Because
they are often misdirected or forced beyond
their limits, they notoriously cause
perforations or break in the hands of
neophytes.
Two of the most historic & popular
engine-driven instruments are Gate Glidden
drills & Pesso reamers (drills).
Gate Glidden drills are an integral part of new
instrumentation techniques for both initial opening of canal orifices
& deeper penetration in both straight & curved canals. Gate-
Glidden drills are designed to have a weak spot in the part of the
shaft closest to the handpiece so that, if the instrument separates,
the separated part can be easily removed from the canal. They
come in size 1 through 6, although these sizes are being
converted to the ISO instrument sizes & colors.
1
Reciprocating Handpiece:-
A commonly used flat plane reciprocating
handpiece is the Giromatic. It accepts only latch-
type instruments. In this device, the quarter-turn
motion is delivered 3,000 times per minute. More
recently, Kerr has introduced the M4 safety
handpiece, which has a 30-degree reciprocating
motion & a unique chuck that locks regular hand
files in place by their handles.
Vertical Stroke Handpiece:-

Levy introduced a handpiece that is driven either by air or
electrically that delivers a vertical stroke ranging from 0.3 to
1mm.The more freely the instrument moves in the canal, the
longer the stroke. The handpiece also has a quarter-turn
reciprocating motion that "kicksin", along with the vertical stroke,
when the canal instrument is under bind in a tight canal. If it's too
tight, the motion ceases, & the operator returns to a smaller file.
Ultrasonic & Sonic Handpiece:-

Ultrasound has been used to activate specially designed
files. Ultra sound consists of acoustic waves which have a
frequently higher than can be
perceived by a human ear. The
acoustic energy is transmitted to
the root canal instrument, which
oscillates at 20-40,000 cycles
per second, depending on which
unit is used.
Research into the
potential mechanisms of
ultrasonic action has continued
and has revealed that is not
cavitation, but a different
physically phenomenon, acoustic
streaming that is responsible for
the debridement. Clearly,
acoustic streaming depends on
the free displacement amplitude
of the file, and if the vibrating file is at least partially constrained
and dampened in its action, it will become ineffective. Irrigation
with sodium hypochlorite is necessary, although some of the
2
ultrasonic units are not designed to accept sodium hypochlorite
through the system and, if water is used, they will be less efficient
in their cleansing effect. Even when units designed to take sodium
hypochlorite are used, daily maintenance must be carried out to
prevent damage, particularly to metals, because the irrigant is
corrosive. The irrigant passes down the shank of the instrument
and into the root canal, producing a continuous and most efficient
system.
Sonic hand pieces:-
Sonic endodontic handpieces attach to the regular airline at

a pressure of 0.4 MPa. Air pressure may be varied with an
adjustable ring on the handpiece to give an oscillatory range of 1.5
to 3KHz. Tap water irrigant/coolant is delivered into the preparation
from the hand piece. The sonic file oscillated in a large elliptical
motion at the tip, out in the air. However, when loaded, as in a
canal, they found that the oscillatory motion changed to a
longitudinal motion up and down.
The principal Sonic endodontic handpiece available today is
the Micro Mega 1500 Sonic
Air Endo System. Like the air
rotar handpiece, it attaches to
the regular airline at a
pressure of 0.4 MPa. The air
pressure may be varied with
an adjustable ring on the
handpiece to give an
oscillatory range of 1,500 to
3,000 cycles per second. The
three choices of file that are
used with the Micro Mega 1500 are the :-
1-Rispisonic which resembles the old rat-

tail file.
2-The sharper Sonic resembles a husky
barbed broach.
3-The Trio Sonic resembles atriple-helix
hedstroem file. All of these instruments
have safe-ended non cutting tips.
3
Laser Endodontics:-
In 1971, at the University of Southern California, Weichman &
Johnson were probably the first researchers to suggest the use
of lasers in endodontics. A preliminary study was undertaken to
attempt to retroseal the apical orifice of the root canal using an
Nd: YAG & a carbon-dioxide laser. Although the goal was not
achieved, relevant data were obtained. In 1972, Weichman et
al. suggested the occurrence of chemical & physical changes of
irradiated dentin. The same laser wave lengths were then used,
with different materials, in an attempt to seal internally the
apical constriction.
Applications of lasers in endodontic therapy have been
aggressively investigated over the last two decades. According
to Stabholz, there are three main areas in endodontics for the
use of lasers: (1) the
periapex, (2) the root
canal system, & (3) hard
tissue, mainly the dentin.
One of the major concerns
of endodontic therapy is to
extensively clean the root
canal to achieve necrotic
tissue debridement &
disinfection. In this sense,
lasers are being used as a coadjuvant tool in endodontic
therapy: (1) for bacterial reduction, & (2) to modify the root
canal surface. The action of different types of laser irradiation
on dental root canals "the carbon" dioxide laser, the Nd: YAG
laser, the argon laser, the excimer laser, the holmium: YAG, the
diode laser & more recently, the erbium: YAG laser has been
investigated.
Unlike the carbon-dioxide laser, the Nd:YAG, argon, excimer,
holmium,& erbium laser beams can be delivered through an
optical fiber that allows for better accessibility to different areas
& structures in the oral cavity, including root canals. The
technique requires widening the root canal by conventional
methods before the laser probe can be placed in the canal. The
fibers diameter, used inside the canal space, ranges from 200
to 400mm, equivalent to a No. 20-30 file.
Thank you
4
Endodontics
Lec: 12
In 1988, the properties of a file manufactured from nickel-

titanium (Ni-Ti) alloy were reported this file demonstrates greater
elastic flexibility in bending, and greater resistance to torsional
fracture than stainless steel. There are now several commercial
versions. Ni-Ti files tend to straighten curved root canals less than
stainless steel file.
Hand NiTi ProTaper system: the proTaper system consist of multiple

instrument sizes , three shaping files & five finishing files .
Shaping files: the shaping files are labeled S-x, S-1, S-2.
the S-x shaper is an auxiliary instrument used in canals of teeth with shorter
roots or to extend & expand the coronal aspects
of the preparation, similar to the use of Gates-
Glidden drills or orifice openers. The S-x has a
much increased rate of taper from D0 (tip
diameter) to D9 (9.0mm point on the blades)
than do the other two shaper S-1&S-2. At the
tip (D0), the S-x shaper has an ISO diameter of
0.19mm. This rises to 1.1mm of D9
(comparable to the tip size of a size 110 ISO
instrument). After D9, the rate of taper drops off up
to D14, which thins & increases the flexibility of the
instrument.
The S-1 & S-2 files start at tip sizes of 0.17mm &
0.20mm, respectively, & each file gains in taper up
to 1.2mm. But unlike the consistent increase of taper
per millimeter in the ISO instruments, the Pro Taper
shapers have increasingly larger tapers each
millimeter over the 14mm length of their cutting
blades. This is what makes the instruments unique.
Shaping file S-1 is designed to prepare the coronal
one-third of the canal where as shaping file S-2
1
enlarges & prepares the middle third in addition to the critical coronal region of
the apical third. Eventually, both size instruments may also help enlarge the
apical third of the canal as well.
Finishing files: the finishing files have been designed to plane away the
variations in canal diameter in the apical one-third. Finishing files F-1, F-2, F-3,
F-4&F-5 have tip diameters (D0) of ISO sizes 20, 25, & 30, 40, and 50
respectively, their tapers differ as well. Between D0 & D3, they taper at rate of
0.07, 0.08, 0.09, 0.06 & 0.05mm/mm, respectively. From D4 to D14, each
instrument shoes a decreased taper that improves its flexibility.
Although primarily designed to finish the apical third of the canal, finishers
do progressively expand the middle third as well. Generally, only one instrument
is needed to prepare the apical third to working length, & tip sizes will be selected
based on the canals curvature & cross-sectional diameter.
Pro Taper Benefits:

1-The progressive (multiple) taper design improves flexibility & "carving"
efficiency, an important asset in curved & restrictive canals.
2-The balanced helical angles of the instrument optimize cutting action while
effectively augering debris coronally,
as well as preventing the instrument
from screwing into the canal.
3-Both the "shapers" & the "finishers"
remove the debris & soft tissue from
the canal & finish the preparation
with a smooth continuous taper
4-The triangular cross-section of the
instruments increase safety, cutting
action, & tactile sense while reducing
to lateral contact area between the file
& the dentin.
5-The modified guiding instrument tip
can easily follow a prepared glide
path without gouging side walls.
2
MANUAL PROTAPER: DIRECTIONS FOR USE
1) Fill the pulp chamber with either Glyde or Sodium Hypochlorite (NaOCl) for all
initial negotiation procedures. Explore the coronal two-thirds of the canal with
stainless steel Nos. 10 and 15 hand files, using a reciprocating back and forth
motion. Work those instruments passively and progressively until they are loose.
2) Start the ProTaper sequence with S1 (purple). The apical extent of S1 will
passively follow the portion of the canal secured with hand files. S1 is designed
to cut dentin, in a crown down manner, with its bigger, stronger and more active
blades. Irrigate, recapitulate with the 10K File to break up debris, then re-irrigate.
3) Manual ProTaper Handle Motion: a. Use a clockwise motion and gently rotate the
handle until it is just snug. When the handle is snug, the flutes of the file are
lightly engaging dentin. b. Cut dentin by rotating the handle clockwise while
simultaneously withdrawing the file. c. If over-engaged, disengage the file by
rotating the handle counterclockwise 45-90 degrees while concomitantly
withdrawing the instrument to prevent any given file from inadvertently
advancing deeper into the canal. d. Repeat the handle motions until desired
length is achieved. e. Depending on the length, curvature, and diameter of any
given canal, it may require one or more passes to carry a file to the desired depth.
4) In more difficult canals, one, two or three recapitulations with S1 may be

necessary to pre-enlarge the coronal two-thirds of the canal. Frequently clean the
blades, then continue using this file until it reaches the depth of the 15 hand file.
Irrigate, recapitulate and then re-irrigate.
5) Once the pre-enlargement procedure is finished, use a pre-curved No. 10K File in
the presence of NaOCl or Glyde to negotiate the rest of the canal and to establish
patency. Determine working length with No. 15K File.
6) When a smooth glide path to the terminus is verified, sequentially carry first S1
then S2 to the full working length. Remember to irrigate, recapitulate and re-
irrigate after each ProTaper instrument.
7) With the canal flooded with irrigant, work the F1 (yellow 20/07) to length in one
or more passes. If the F1 ceases to advance deeper into the canal, remove the
3
file, clear its blades, then continue with its use until it reaches length. Irrigate,
recapitulate and re-irrigate.
8) Following the use of F1 to length, gauge the foramen with a 20 hand file. If the
20 hand file is snug at length, the canal is shaped and ready to fill. If the 20 hand
file is loose at length, proceed to the F2 and, when necessary, the F3, gauging
after each Finisher with the 25 and 30 hand files, respectively.
4
Endodontics
Lec:13
Root canal filling

The overall function of a root filling is to occupy the instrumented
root canal space to allow proper healing of the periapical tissue.
Specifically it attempts:
(1) To prevent leakage of bacterial organisms, bacterial elements and
nutritional elements from the oral environment to the root canal (coronal
leakage).
(2) To restrain growth of any surviving bacteria in dentinal tubules and
uninstrumented parts of the root canal space.
(3) To prevent release of bacterial elements in the other direction, i.e.
from the root canal to the apical environment (apical leakage).
(4) To prevent leakage of nutritional elements from the periapical
tissue to the canal space.
Criteria for obturation:-

It would seem sensible to delay obturation of teeth in the following
categories:
1- Teeth with signs of apical periodontitis, e.g. those with tenderness
to apical palpation.
2- Teeth associated with radiographic signs of apical periodontitis.
3- Teeth with excessive exudates that cannot be stopped.
4- Teeth with a purulent discharge into the canal.
5- Teeth associated with a procedural accident, e.g. perforation.
1
Functions of root canal sealer:-
Root canal sealers are used in conjunction with core filling
materials for the following purposes:
1- Cementing (luting, binding) the core material into the canal.
2- Filling the discrepancies between the canal walls and core material.
3- Acting as a lubricant to enhance the positioning of the core filling
material.
4- Acting as a bactericidal agent.
5- Acting as a marker for accessory canals, restorative defects, root
fractures and other spaces into which the main core material may
not penetrate.
The properties of an ideal sealer are:
1-exhibits tackiness when mixed to provide good adhesion between it and

the canal wall when set
2-establishes a hermetic seal
3-radiopacity so that it can be seen on the radiograph
4-very fine powder so it can mix easily with the liquid
5-no shrinkage on setting
6-no staining of tooth structure
7-bacteriostatic, or at least dose not encourage bacterial growth
8-exhibits a slow set
9-insoluble in tissue fluids
10-tissue tolerant; that is, nonirritating to periradicular tissue
11-soluble in a common solvent if it is necessary to remove the root canal
filling.
Currently used root canal sealers may be divided into:
*Zinc-oxide-eugenol (ZoE) based materials have long been considered

the sealer of choice in endodontic therapy. An advantage to this sealer
group is its antimicrobial activity. Once set, zinc oxide-eugenol sealers
form relatively weak, porous materials which are susceptible to
decomposition in tissue fluids particularly when forced into the
periradicular tissues. They exhibit a slow setting time, shrinkage on
setting , solubility, and they can stain tooth structure. All zinc oxide-
eugenol cements are cytotoxic and the response may last longer than
those produced by other materials.
*Resin-based sealers
Epoxy resin sealers have comparatively good mechanical and sealing
properties. No effects on general health are expected and allergic
2
reactions are apparently rare, also antimicrobial properties are good,
especially in a freshly mixed state. Cytotoxicity is moderate to low.
AH26 is an epoxy resin that was initially developed as a single obturation
material. Because of its positive handling characteristics, it has been
extensively used as a sealer. It has a good flow, seals well to dentin walls,
and has sufficient working time. AH Plus is a modified formulation of
AH26 in which a formaldehyde is not released. AH Plus is a two-
component paste/paste root canal sealer based on epoxy-amine resin, it is
an improved modification of its precursor AH26 and shows a high flow.
The sealing abilities of AH-26 and AH Plus appear comparable; it
exhibits a working time of approximately 4 hours. AH Plus have been
shown to have lower solubility than ZoE and calcium hydroxide sealers
along with an adequate working time.
Recently, new dentin-adhesive root canal cements have been introduced
to enhance the bond between the core
material of gutta-percha and the root
canal walls. Example is Epiphany,
which are resin based materials with
hydrophilic properties. Epiphany may
also be combined with a synthetic
polymer-based root canal filling
material (Resilon) in the Epiphany–
Resilon system. Resilon mainly
consists of polymers of polyesters
(polycaprolacton) and bioactive glass,
giving this material physical property
similar to those of guttapercha. This
means that it can be used cold or plasticized by heat. While a promising
development, research documentation has so far primarily been based on
in vitro and animal studies observing sealing biocompatibility aspects.
Independent clinical research has yet to show superiority of these
materials to traditional products with gutta-percha as the core material.
*Calcium hydroxide sealer: Calcium

hydroxide sealers were developed for
therapeutic activity. It was thought that
these would exhibit antimicrobial
activity and have osteogenic-
cementogenic potential. Solubility is
required for release of calcium
hydroxide and sustained activity; this is
inconsistent with the purpose of a
sealer. Examples of these are Calciobiotic root canal sealer, Apexit and
3
Sealapex. Mechanical properties of calcium hydroxide sealers are
inferior compared with GIC based sealers. The desired release of OH ions
may be associated with degradation of the sealer, enhancing leakage.
Degradation of salicylate-based materials is known from their application
as pulp capping agents. Studies clearly indicate significant volumetric
expansion, disintegration and high solubility of a calcium hydroxide
sealer following long-term observations. Apparently, some calcium
hydroxide sealers dissolve at a relatively high rate, especially when used
in a thick layer.
*Glass ionomer sealers

Pitt Ford in 1979 introduced a glass-ionomer (GI) sealer in a single-cone
technique. It is the only self-adhesive material currently available that
eliminates the need for a separate adhesive system. Glass ionomer
adheres to dentin through physical and chemical interaction; physical
interaction is through a micromechanical interlocking of the material to
tooth surface irregularities, while chemical interaction occurs when
polyacrylate ions of GIC displace existing phosphate ions in the
hydroxyapatite crystal and attached to dentin. The sealing ability of GIC
sealers have been equivocal; demonstrating both advantages and
disadvantages over other sealer types. Dental applications of GI sealers
take advantage of their bond to dentin, fluoride release, antimicrobial
activity, and biocompatibility. A disadvantage of GI sealer is that they
must be removed if retreatment is required. Examples of these are root
canal sealer, (Ketac Endo and Activ Gp).
Activ GP is a system which utilizes improved GI technology (both as a
sealer and as a special GI coated gutta-percha cone) to create a true single
cone monoblock obturation. Activ GP sealer is superior to previous GI-
based systems in terms of handling characteristics, working time,
radiopacity, and seal, because of the increased of its flowability.
Activ GP Sealer is used in powder and liquid formulation. It is
formulated with an extended 15 minute working time. The natural
adhesion of GI to dentin (ionic bond) means there’s no need for a
bonding agent (primer) and the associated application technique
challenges.
*Bioceramic sealer
Bioceramic sealer (BC) has been designed as non-toxic hydraulic calcium
silicate cement that is easy to use as an endodontic sealer. Among the
attributes of BC Sealer are improved convenience and delivery, and the
advantage of utilizing the water inherent in the dentinal tubules to drive
the hydration reaction (of the material) thereby shortening the setting
time. The calcium silicates in BC Sealer hydrate with water to produce
4
calcium silicate hydrate gel, which forms a chemical bond with the
calcium aluminate and calcium silicate compounds on the surface of the
coated gutta-percha. Also the BC sealer will bond to dentinal walls; the
calcium silicate hydrogel will form a chemical bond with the
hydroxyapatite because of the hydroxy-group. Therefore, both of the
compounds will form chemical bonding with the dentin hydroxyapatite
The properties of an ideal filling material:

1-easily manipulated and provides ample working time
2-dimensionally stable with no shrinkage once inserted
3-seals the canal laterally and apically, conforming to its complex internal
anatomy
4-non irritating to the periapical tissues
5-impervious to moisture and nonporous
6-unaffected by tissue fluids- no corrosion or oxidation
7-inhabits bacterial growth
8-radiopaque and easily discernible on radiographs
9-dose not discolor tooth structure
10-sterile
11-easily removed from the canal if necessary
Gutta – Percha:-
Gutta-percha has been used to fill root canals for over 100 years
and is the most widely used and accepted obturation material. Gutta-
percha is a form of rubber obtained from a number of tropical trees. It is a
trans isomer of polyisoprene which, in its pure form, is hard, brittle and
less elastic than cis-poly isoprene, natural rubber. It is exists in two
crystalline form (alpha and beta). It is mixed with a variety of other
materials to produce a blend which can be used effectively within the root
canal. Thus, the points of gutta-percha available commercially contain
gutta-percha (20%), zinc oxide (65%) and various waxes, coloring
agents, antioxidants and metal salts (10%) to provide radiopacity. The
proportions of the constituents vary from brand to brand, with the result
that there is considerable variation in the stiffness, brittleness and tensile
strength of commercially available gutta-percha points.
Gutta-percha points have many advantages as they are:

1-Inert.
2-Dimensionally stable.
3-Non-allergenic.
4-Antibacterial.
5-Non-staining to dentine.
6-Radiopaque.
5
7-Compactable.
8-Softened by heat.
9-Softened by organic solvents.
10-Removable from the root canal when necessary.
As with all materials gutta-percha points have some disadvantages as
they:
1-Lack rigidity.
2-Do not adhere to dentine.
3-Can be stretched.
For root canal obturation, gutta-percha is manufactured in the form of

cones in both standardized
and non standardized sizes.
The standardized sizes
coordinate with the ISO
sizes of the root canal file
sizes 15 through 140 and
are used primarily as the
main core material for obturation. Recently
standardize cones are designed to match the taper of nickel titanium
instruments (standardized cones# o6, taper, sizes # 15 to #40. ,
standardized cones protaper S1, S2, S3, S4, S5). The non standardized
sizes are more tapered from the tip or
point to the top, and they are usually
designated as extra-fine, fine-fine,
medium-fine, fine-medium, medium,
medium-large, large, and extra-large.
With some obturation techniques these
cones are used as accessory or auxiliary
cones during compaction, being
matched with the shape of the prepared canal space or the compaction
instrument. Although the standardized cones have been popular for years
(since the standardization of the file system), non standardized cones
have assumed a greater role as the primary core material in the more
contemporary obturation techniques. With the development of these
techniques, in particular those of vertical compaction with heat softening
of gutta-percha, there has been a resurgent interest in the non
standardized cones. For injectable thermoplastic obturation techniques,
gutta-percha may come in either pellet form or in cannulas. For some
thermo mechanical techniques, it is available in heatable syringes.
6
Coated gutta-percha
1-Resin coated gutta-percha: contain gutta-percha, zinc oxide, barium
sulphate and coloring agents and are entirely coated with a thin layer of
polymerized urethane dimethacrylate resin (UDMA).
2-Activ GP gutta-percha: consists of gutta-percha cone impregnated in
the external surface with glass ionomer (GI).
3-Bioceramic coated gutta-percha: is a new type of coated gutta-percha it
is subjected to a patented, proprietary process of impregnating and
coating each cone with BC nanoparticles.
Silver points:-
Silver points made to standardized sizes were introduced in the
1930s as a method for filling fine tortuous canals. With the instruments
and preparation techniques available at the time, such canals were
difficult to enlarge adequately in order to accept gutta-percha pints. The
rigidity provided by the silver cones made them easy to place and
permitted length control; however, their inability to fill the irregularly
shaped root canal system permitted leakage. When silver points contact
tissue fluid or saliva they corrode. The
corrosion products have been found to
cytotoxic and produce pathosis or impeded
perapical healing.
With the introduction of the rigid silver
cones it became possible to easily place them
to length. This resulted in clinicians often
failing to properly clean and shape the canal
before obturation. The use of silver cones is considered to be below the
slandered of care in contemporary endodontics practice.
7
Endodontics
Lec.14
Canal obturation with gutta-percha
The objective of canal obturation is to fill completely the canal system in
an attempt to seal the canal from leakage in apical and coronal directions.
Gutta-percha can be used in a variety of techniques because of its
versatility; however, it must be emphasized that a sealer is always
required to lute the material to the canal wall and to fill minor
irregularities which cannot be filled by gutta-percha itself.
In recent years a large number of filling techniques have described,
often accompanied by unsubstantiated claims of greater efficacy, reduced
leakage or improved economics. Although it is essential to strive for
improved filling techniques, the clinician must be aware that newer does
not necessarily mean better. Indeed, there is little evidence from clinical
trials to suggest that any differences exist between the techniques in terms
of the ultimate success or failure of the procedure. In general terms,
clinicians should be cautious in their approach to new filling techniques
and await the outcome of laboratory and/or clinical studies before
adopting a new regime.
Broadly speaking, techniques of filling canals with gutta-percha
can be divided into three main groups:
1- Use of cold gutta-percha.

2- Use of heat-softened gutta-percha.
3- Use of solvent-softened gutta-percha.
Cold gutta-percha techniques

Cold gutta-percha techniques are generally simple to master as they are
not complicated by needing to soften the material with heat or solvents;
neither do they require expensive and often complicated devices or
equipment. However, it should be clear that cold gutta-percha cannot be
compacted into irregularities within the canal system, with the result that
this role must be fulfilled entirely by sealer.
Cold gutta-percha can be used in a number of techniques:
-1-
1- Full-length single point.
2- Apical (sectional) single point.
3- Lateral condensation.
Full-length single point:

With the advent of the standardized preparation technique, the method
of filling canals with a single full-length gutta-percha point and sealer
became popular. The theory behind the technique was simple and
attractive; the canal was prepared to a round
cross-sectional shape of standard size by use of
reamers and then obturated by a gutta-percha
point of matching diameter. However, it soon
became apparent that a round canal shape was
rarely a chivied, especially in curbed canals, and
that single –point obturation was likely to be less
than idle as it would rely inevitably on
substantial amounts of sealer to fill the gaps,
resulting in increase leakage. It was also clear that discrepancies in size
and taper between points and equivalent numbered instruments were
prevalent.
Current canal preparation techniques which aim to flare canal to

produce a flowing conical funnel shape cannot be filled adequately with a
single-point technique using zinc oxide or calcium hydroxide-based
sealers, and therefore should not be attempted.
Apical (sectional) single point:

In a tooth scheduled for restoration with a post crown, substantial part of
the canal must be available to accommodate the post. The apical 4-5 mm
of a point was cut off and then mounted on the end of a file before being
introduced into the canal. Once the gutta-percha point seated at the end–
point of preparation the file was rotated, detached from the gutta-percha
and removed. The technique was unpredictable and suffered from the
same problems as the full-length point technique in terms of lack of fit.
Therefore, use of an apical (sectional) single point is not recommended.
-2-
Lateral condensation:
Lateral condensation of cold gutta-percha is taught and practiced

throughout the world and is the technique of choice for many clinicians.
It is simple and rapid to carry out, can be used in virtually all cases and is
the standard against which many new techniques are compared.
Lateral condensation involves the placement of a
master (primary) point at the end-point of preparation
followed by the insertion of additional (accessory)
points alongside. The use of a standardized master
point provides a predictable apical fit, whereas the
accessory points obturated the space produced as a
result of the flared canal shape. The resultant filling
consists of numerous points cemented together and to
the canal wall by sealer; it does not result in a merging of the points into a
homogeneous mass of gutta-percha.
A spreader is interested alongside the master point to improve the
adaptation of the master point at the end-point of preparation and to
create the space for accessory points. When
inserted to within 1mm of the end-point of
preparation, the spreader compacts
effectively the master point apically and
laterally, resulting in considerably less
leakage than if the spreader had only entered
part-way into the canal. In fact, the necessity
to advance the spreader well into the canal is the only reason why canals
are flared; a narrow, parallel canal shape would not allow a spreader to
advance sufficiently to influence the adaptation of the apical region of the
master point. Narrow preparations also predispose to the unwanted
removal of the master point upon withdrawal of the spreader as it tends to
pierce the master point rather than lie alongside it.
The requirements for successful lateral condensation are therefore:

1- A flared canal preparation with a definite apical stop.
2- A well-fitting master gutta-percha point of standard size and taper.
3- A series of spreaders of the appropriate size and shape.
4- An assortment of accessory points which match the size and taper of
spreaders.
5- An appropriate sealer.
Well-fitting master point. The master point must fit to the full length of
the preparation, be tight at the end-point of preparation, and it must be
impossible to force it through the foramen.
-3-
The size of the master point is guided by the master apical file used
in the final preparation of the apical stop or matrix. The selected point is
held with tweezers at a length equivalent to the working distance and then
inserted into the canal. Ideally, the point should:
1- Pass down to the full working distance so that the beaks of the
tweezers touch the reference point.
2- Be impossible to push beyond this position, i.e. through the
foramen.
3- Fit tightly at the end-point of preparation, giving some resistance to
withdrawal (tug back).
The tweezers are squeezed slightly so as to notch the point and are then
released leaving the point in situ. A radiograph is then exposed to
confirm its position in relation to the end-point of preparation and the
radiographic apex. Theoretically, if the original estimate of the
working distance was corrected, the point should be in the appropriate
position and canal obturation can proceed. Some authorities condense
the master point with a spreader prior to taking the radiograph in order
to ensure that it reaches the end-point of preparation.
*Point reaches working distance but is loose. This may occur for a
number of reasons.
1) The gutta-percha point was smaller than expected. During the

manufacture of points- a tolerance of + 0.05 mm is allowed at d 1 so
that it is possible for the point with correct nominal size to be
smaller than the equivalent file size and prepared canal width. The
solution is to try-in a selection of other points of the same size in the
hope that one of the correct size will be found; to remove 1mm
increments off the tip of the point with a sharp blade to increase the
tip diameter; or to try-in a point of larger nominal diameter. If points
are reduced in length, care should be taken to ensure that the tip has
not been flattened before it is re-inserted into the canal.
2) The end point of preparation was wider than expected. Just as the
size of points may vary, so can the size of files. The tolerance of
files can be + 0.02 mm at d1 so that it is possible for the canal to be
wider than anticipated. The solution is the same as described above.
The canal can become wider than expected through inappropriate
choice of instruments and/or preparation technique, leading to the
removal of excess dentine from the outer wall of the canal apically.
Should this problem be identified, and then either a selection of points
-4-
can be tried-in until one is found to fit, or an alternative filling method
chosen.
*Point passes beyond working distance through foramen. This can

occur when the apical stop is inadequate or when the point is too small.
If the stop is not sufficiently definite, then the point will pass more
deeply into the canal and through the foramen. The solution is either to
reprepare the canal with larger instruments until a distinct stop is
created at the end-point of preparation or to remove 1 mm increments
from the point until its diameter is sufficient to bind in the canal at the
working distance. In general terms the creation of a definite apical stop
is the solution of choice.
*Point does not reach working distance. This is the most common
problem which occurs with the positioning of the master point, and
there are a number of reasons:
1- Straightening of curved canals. During the preparation of curved
canals it is likely that some Straightening of the curve will occur as
the instruments tend to remove more dentine from the outer curve
apically and from the inner curve in the mid-root. Clearly, a
straighter canal will become shorter as the files will pass along its
length in a more direct manner to the end-point of preparation. The
exact degree of straightening cannot be predicted with certainty and
will vary depending on the curvature of the canal, when the canal
length was measured and the suitability of the shaping procedure.
However, it is likely that with most preparation techniques,
approximately 0.5 mm of length will be lost in moderately and
severely curved canals. It is obvious that this reduction in length
should be taken into account during the preparation stage and at the
time of obturation. During the selection and try-in of a master apical
point in a curved canal an adjustment should be made to the length
in order to take account of this phenomenon and a radiographic
check on position completed before any attempt is made to achieve
the original working length through further canal preparation.
2- The point was larger than expected. Just as points can be smaller
than the nominal size and appear loose, they can also be larger and
not seat fully. Thus, if a point is a short distance (> 2mm) away
from the end-point of preparation it may be possible to try a
selection of points of the same nominal diameter in the hope of
finding one that fits.
3- The canal was not widened sufficiently at the end-point of
preparation. This is a common problem and occurs when the master
apical file is either smaller than its nominal size or, more likely, that
-5-
it was not used sufficiently to widen the canal fully. It is essential
that the master apical file is manipulated until it can pass down
freely to the end-point of preparation without any undue force being
applied. With insufficient preparation it may be possible to force the
master apical file to the working distance; however, if the same
technique is adopted with a gutta-percha point then it will bind and
buckle short of the expected length. The solution to this problem is
to select a new file and reinstrument the canal to the working length
until the file is loose.
4- Dentine debris is blocking the apical region of the canal. This is
another common problem which occurs as a result of insufficient
irrigation. Prevention is better than cure as many blockages are
difficult to eliminate. Thus, during canal preparation copious
volumes of irrigant should be used and canal preparation should
include frequent and effective recapitulation at the end-point of
preparation. The solution to this problem is to irrigate the canal
thoroughly and then to manipulate gently small files deep within the
canal in an attempt to disrupt the compact dentine and float out the
debris in the irrigant. These small files can be rotated to improve
their effectiveness but great care should be exercised to prevent the
files creating their own canal and perforating the canal wall. This
procedure is time-consuming and potentially dangerous in curved
canals and the use of large inflexible files with sharp tips must be
avoided. Endosonic devices enhance debris removal and are more
likely to clear canal blockages.
Selection of spreaders and accessory gutta-percha points: Once the

master apical point has been selected, it is important to select and try-in
the spreader in order to insure that it can pass down the canal to within 1
mm of the end-point of preparation. Spreaders should be precurved in
curved canals and a rubber stop used to identify the length of insertion.
To eliminate the risk of root fracture, excessive condensation pressure
should be avoided by the use of finger spreaders.
Spreaders are either manipulated with fingers
(like files) or have long handles. The working part can
have a non-standardized taper or standardized
international organization for standardization (ISO)
0.02 taper, the same as most files. Non-standardized
spreaders have relatively small diameters at the tip but a
range of tapers from extra-fine through fine, medium to
large; some manufactures use letters rather than words
to denote the degree of taper, e.g. A-D. Spreaders
with a standardized taper are manufactured with ISO diameters such as
-6-
size 20 up to size 40.The choice of spreader design, that is, with non-
standardized taper, is determined by operator preference and the type of
accessory points to be used. When non-standardized spreaders are used
the points should be non-standardized; however, standardized spreaders
require standardized accessory gutta-percha points. In this way the space
created by the spreader will be filled by the point. It is important to
realize that space created by standardized spreader cannot be filled
adequately with a non-standardized point. It is sound clinical practice to
use spreaders and points from the same manufacture to ensure
compatibility.
The size of spreader, and thus points,
is determined by the size of the canal. Large
canals with substantial taper are more
efficiently filled with more tapered points,
whilst smaller canals with narrower tapers
should be filled by finer points. On most
occasions an extra-fine or fine (A, B) spreader is required along with
matching points.
Completion of lateral condensation
The initial phases of lateral condensation have already been described.

After these preliminary stages, the filling procedure is relatively
straightforward:
1- The master point, spreader, accessory
points and sealer should be carefully
arranged to ensure that they can be handled
efficiently.
2- The canal should be dried thoroughly
with paper points. Use of alcohol to promote effective drying is not
recommended for inexperienced operators.
3- The sealer should mix, carried into the
canal and smeared (buttered) onto the canal
wall. Sealer application can be achieved
using a hand file rotated anti-clockwise, by
coating a paper point and inserting into the
canal, or by coating the master point itself.
There is no need to apply a large volume of
sealer with spiral filler.
4- The master point should be buttered
lightly with sealer and then inserted
immediately to the full distance so that to
-7-
notch made by the tweezers lies at the reference point.
5- The spreader is then placed alongside the point and pushed
apically with controlled force until it reached the appropriate depth,
1 mm from the end-point of preparation. The direction of force
should be apical with no lateral rocking of the spreader to prevent
root fracture. In straight canals the spreader can be rotated at the
same time as being pushed apically; however, this is contraindicated
in curved canals. Apical pressure should be applied in a constant
manner for approximately 10 s to achieve the appropriate
compaction of the gutta-percha in an apical and lateral direction. In
curved canals the spreader should be applied either lateral to or on
the outer aspect of the master point; it should not be
applied along the inner aspect of the curve or the
spreader is likely to pierce the point and drag it out
subsequently.
6- The first accessory point should be inserted into

the space created by the spreader and seated fully.
7- The spreader is then cleaned and reinserted
immediately into the canal as described above. On
this occasion the spreader will not enter the canal to the
same length.
8- The second accessory point is inserted into the
space.
9- The sequence of spreader application and point
insertion continuous until the canal is full. The number
of additional points required will vary from case to
case.
10- If the final restoration is not post-retained, the excess
gutta-percha emerging from the canal should be removed with a hot
instrument and condensed vertically at the
orifice with a plugger that fits the canal tightly
to ensure a satisfactory coronal seal. In
anterior teeth the gutta-percha should be
reduced to below the gingival level in order to
maintain the translucency of the crown and to
prevent the possibility of sealer staining the
dentin; in posterior teeth the gutta-percha
should be seared off at the canal orifice.
Lateral condensation is relatively

simple to carry out, rapid, and has
been used for many years with
-8-
considerable success. However, since it is impossible for cold gutta-
percha to flow into irregularities within the canal system, parts of the
canal must either remain unfilled or be filled only with sealer which
has been forced into these regions by the pressure exerted through the
insertion of spreaders and points.
Thank you
-9-
Endodontics
lec.15
Heat softened gutta-percha techniques

For many years, the only technique which used heat-softened
gutta-percha was that of warm vertical condensation. More recently, a
large number of innovative methods of warming and condensing gutta-
percha have been described. Some techniques involve placing cold gutta-
percha into the canal and then warming it in situ; these can be referred to
as intracanal heating techniques, whilst others rely on warming gutta-
percha outside the canal before its placement-the extracanal heating
techniques.
It must be emphasized that for most canals lateral condensation of
gutta-percha is the method of choice. In general, the heat-softened
techniques are technically more difficult and should be used with caution
by inexperienced and non-specialist operators. Prior to use in patients the
techniques must be practiced in simulated canals and extracted teeth to
ensure competency.
Intracanal heating techniques:

These techniques include all those where cold gutta-percha is
inserted into the canal and then heated within the canal so that it becomes
softened and condensable. All the techniques are used conjunction with
sealer.
Warm lateral condensation:

Warm lateral condensation relies on a heated spreader to warm
gutta-percha during lateral condensation and so achieve better adaptation
of the material and a homogeneous mass of gutta-percha.
In its simplest form a conventional
spreader can be heated in a glass bead heater or
the cool part of a flame and then placed
alongside the master apical point just as in the
conventional cold technique. The heat softens
the gutta-percha whilst the vertical and lateral
action of the spreader creates space for additional points. Repeated
insertion of the heated spreader should allow movement of the gutta-
percha apically and laterally into irregularities whilst the additional points
provide sufficient mass of material to obdurate the entire system
-1-
effectively. Some operators prefer to insert several cold accessory points
prior to the use of heat. This technique can be difficult to master since
gutta-percha tends to stick to the heated spreader and may become
dislodged when the spreader is removed. Continual movement of the
spreader is advocated to prevent this problem.
More refined techniques of
warm lateral condensation involve
the use of electrically heated
spreaders. The first device for this
purpose was the Endotec, a battery-
operated system in which the
application of heat was controlled by
an activator button.
Warm vertical condensation:-

The aim of this technique is to obliterate the canal with heat-
softened gutta-percha packed with sufficient vertical pressure to force it
to flow into the entire root canal system, including accessory and lateral
canals. The traditional technique requires a widely flared canal
preparation with a definite apical stop. The flared nature of the canal is
necessary to accommodate the pluggers used to condense the gutta-
percha, whilst the apical stop is essential to restrict movement of gutta-
percha through the foramen. Excessive widening of the canal at the end-
point is counterproductive and actually results in more apical leakage and
an increased incidence of overextensions.
Prior to obturation the appropriate pluggers must be selected and
tried-in. in most cases three pluggers
are used, one to fit in the coronal
region, one in the middle and the
smallest in the apical 3-4 mm. the
pluggers should be used without
binding on the canal wall to prevent
undue pressure on the wall which
might lead to root fracture.
A non-standardized gutta-percha point is then selected and the tip
removed until it fits to within 2-3 mm of the end-point of preparation.
Following sealer application the point is
seated and the excess coronal gutta-
percha in the access cavity and chamber
removed with a hot instrument. A cold
plugger is then used immediately to apply
vertical pressure to the cut, softened end
of the gutta-percha to a depth of 3-4 mm and removed immediately to
-2-
prevent adhesion of material. A cold plugger is then forced against the
warmed surface and vertical pressure applied. In this early stage, the
middle and apical areas of the gutta-percha are not affected so the
procedure is repeated with increasing depth of penetration of the heated
spreader until first the middle and then the apical area is warmed and
condensed vertically. In the process of reaching the apical region much of
the gutta-percha is removed with the spreader so that the middle and
coronal regions must be filled later with small increments of gutta-percha
which are heated and condensed vertically as before.
Rotating condenser:
The use of an engine-driven
rotating compactor to soften and
condense gutta-percha vertically and
laterally was first described by
McSpadden. The technique was
termed thermatic condensation and
relied upon a rotating stainless-steel
compactor generating sufficient
frictional heat within the canal to plasticize the master point and then
drive it apically. The original McSpadden compactors were similar to
Hedstrom files but with the blades directed towards to tip.
The original technique demanded that the condenser was activated
in the canal, alongside the master point, at approximately 12000 rpm
without apical pressure. After a matter of seconds the gutta-
percha became softened and was driven apically by the
controlled advance of the condenser to a point some 2 mm
from the end-point of preparation. As the apical region filled
with material, the condenser tended to back out of the canal,
whereupon the instrument was slowly withdrawn while still
rotating at the optimum speed. In large canals a second point
was condensed in order to fill deficiencies in the middle and
coronal regions.
Extracanal heating techniques:

These rely on gutta-percha being warmed and softened out of the
mouth prior to its insertion within the canal. All the techniques are used
with sealer.
Precoated carriers…
An innovative approach to filling canals uses a stainless-
steel file to carry thermally softened gutta-percha to the tooth. The
original carriers were endodontic files which were coated with gutta-
-3-
percha. The gutta-percha coating the file was gently warmed in the cool
part of a flame until it softened and then the whole unit was inserted into
the canal to the appropriate length. That part of the file emerging from the
canal orifice was then severed and removed, to leave the majority of the
file embedded within the canal surrounded by gutta-percha and sealer.
The efficacy of the technique was based on the flow characteristics of the
gutta-percha and the ability of the carrier to transport and condense the
material. The technique was subsequently modified and made available
commercially.
The present series of carriers are made from nickel-titanium or plastic.

Special gutta-percha coats the shaft of the device, making the warmed
material sticky and adhesive but with excellent flow characteristics. The
system now includes an oven to warm the
obturators in a controlled and reproducible
manner. In addition, a series of uncoated
carriers is provided to check the diameter of
the end-point preparation and to simplify the
selection of the appropriately sized obturator.
Within the last few years a variety of
similarly precoated carriers made by other
companies
*thermafill obturators: it is a flexible carrier corresponds to ISO
standards from size 20 to size 140 at the apical end of the carrier with 4%
tapering. It recommended for long, narrow, curved
canal and ideal for fragile root.
*Thermafil plus obturators: available in two
tapers (4%and 6%), ranging from size 20 to size 90
at the apical end of the carrier.
*GT obturators: are designed to match the shape created

with GT series and ProFile GT series files. Therefore
there is a GT obturator for each file and their three
principle series with apical diameters of 0.2mm, 0.30mm,
and 0.40mm and four tapers (4%, 6%, 8%, and
10%).There is an additional series of three 12%taper
obturators and apical diameters of 0.50mm, 0.70mm and
0.90mm.
*ProTaper universal obturators: are parts of the

complete ProTaper universal family products.
ProTaper obturators are color-coded and precision
-4-
matched to fit the shape created by ProTaper universal files (F1, F2, F3,
F4, F5).
The carrier has longitudinal groove to
allow excess gutta-percha to backflow
coronally, and five rings placed at 18mm,
19mm, 20mm, 22mm and 24mm from the
end in order to facilitate correct insertion
length. Thermafil gutta-percha is hard and
friable in its solid state, but when softened becomes
thermoplastic with excellent properties of flow and low
viscosity.
The technique for using precoated carriers in simple.
Following preparation and drying of the canal, an uncoated carrier is
inserted to the full working distance. If it passes down to the end-point of
preparation without using force, the equivalent size of obturator is
selected and the working distance marked with the silicone stop. The
obturator is then placed in the heating chamber of the oven for the
appropriate time. The canal is dried further, and then coated with a small
amount of sealer placed at
the entrance to the orifice.
The obturator is removed
from the oven and
immediately seated into the
canal until it reaches the
desired length. The excess
gutta-percha in the chamber
is removed and the remainder
condensed vertically to
enhance the coronal seal. After the gutta-percha has cooled, the shaft is
severed with a bur and the handle discarded. The canal preparation is
modified as less coronal flare is required.
Thermoplastic delivery systems:
This technique involves heating gutta-percha to a molten state and
then forcing it under mechanical pressure
(injection) into a relatively cool mould (the
root canal). On dissipation of the heat, the
material solidifies and retains the shape
determined by the internal outline of the
mould. The techniques used in Endodontics for
injecting softened gutta-percha are not true
injection-molding systems as the pressure
applied to the gutta-percha by the delivery
systems is sufficient only to deposit the material into the canal; vertical
-5-
condensation is then required to ensure adaptation of the gutta-percha to
the canal wall and three-dimensional obturation of the canal system.
Injection of gutta-percha produces a seal

comparable to lateral condensation,
although extrusion of material may occur.
The adaptation of gutta-percha to the canal
walls has been confirmed. In a
commercially available delivery system, the
gutta-percha was heated to 160°C and
delivered through the needle tip at
approximately 60°C. The original device has been superseded by the
Obtura II system with improved temperature control.
Solvent-softened gutta-percha:-
Chloroform-softened gutta-percha has a long tradition in
endodontics, and associated filling techniques are still taught in many
institutions and practiced widely. The forerunner of the current methods
was the Johnston-Callahan method of root canal filing. Following
extensive drying of the canal with alcohol, it was filled with a solution of
rosin in chloroform into which was seated a gutta-percha master point.
The chloroform softened the surface of the gutta-percha and made it
swell, and the rosin acted as a glue to make the mass stick to the canal
walls. This method is still taught with only
minor modifications in Sweden, as the rosin-
chloroform filling method.
The high degree of evaporation and the
fluid nature of the rosin solution led to the
development of chloro-percha. Primarily a thick
suspension of fine carvings of gutta-percha in
chloroform, chloro-percha was soon modified by the addition of zinc
oxide and metal salts to act as much as a conventional sealer as merely
softening the points.
Chloroform is also used to aid in the production of custom-formed
master points. This has been popularized as the chloroform dip technique.
In this method the apical 2-5 mm of the master gutta-percha point is
dipped in chloroform for a few seconds and inserted into the canal to the
end-point of preparation. The point is then withdrawn and allowed to dry.
The chloroform softens the outer layer of the gutta-percha so that when it
is seated fully it takes up the shape of the apical portion of the canal.
Because the volume of solvent is small and the thickness of gutta-percha
affected is minimal, there is little shrinkage following solvent
evaporation. The customized point is then cemented in place with a
-6-
conventional sealer and the remainder of the canal filled with laterally
condensed gutta-percha. The apical seal obtained with this technique has
been shown to be comparable with traditional cold lateral condensation.
Apical dentine plug:-

Problems with the biocompatibility of root canal filling materials
and the potential for their extrusion through the foramen into the
surrounding periradicular tissues led to the intentional use of an apical
dentine plug during canal obturation. The apical dentine plug is built up
from clean dentine filing s packed into the apical foramen of the canal
prior to obturation with conventional techniques. The rationale for this
procedure is that dentine filings (shavings), when impinged on the vital
apical pulp stump or periradicular tissue, act as a nidus for the deposition
of cementum or intermediate-type hard tissue, while the plug acts as a
barrier between the root canal filling material and connective tissue.
Studies in experimental animals revealed that packing uninfected
shavings in the foramina stimulated the formation of cementum and bone
at the apex.
Thank you
-7-
-8-
Endodontics
‫ بلند محمد سليم‬.‫د‬
Restoration of Endodontically Treated Teeth (Part 1)

Endodontic treatment is an attempt for preserving a tooth with damaged pulp in
function. Success of endodontic therapy depends upon combination of three
dimension fluid tight obturation along with adequate post endodontic restoration to
make the pulpless teeth to function as an integral part of the dental arch.
Effects of endodontic treatment on the tooth:

1-Structural changes
In general the crowns of endodontically treated teeth could be weakened by caries,
trauma and/or during access cavity preparation. This weakened crown portion
become unable to perform its normal function even after
successful endodontic therapy. This weakened tooth
structure is further prone to fracture. The compromised
structural integrity make the tooth insufficient to perform its
function because of loss of occlusion with its antagonist and
adjacent teeth. Also excessive removal of radicular dentin
during canal preparation compromises the root.
2-Changes in the Dentin Physical characteristics

The endodontic treatment has shown to cause irreversible changes and weakening
of tooth. It is known that the failure rate of restored root-treated teeth can be
higher than for vital teeth. There has always been the belief that the removal of a
pulp from a tooth changes the physical properties of the tooth structure. The
terms "brittle" are used to describe endodontically treated teeth which are the
major reason why fractures are common.
Physical chemistry of dentinal structure also changes following the endodontic
therapy. Radicular dentin possesses less of moisture content than the coronal part
because of fewer tubules, more inorganic part and intertubular dentin. Moisture
content further gets reduced because of aging, decrease in amount of organic
content and increased in inorganic components. There are different opinions on
whether endodontically treated teeth become more brittle because of moisture loss
or caused by loss of pulpal tissue.
that is why we should:-
1) Preserve and protect useful remaining tooth structure.
2) Minimize stress within both tooth and restoration.
3-Aesthetic Consideration
Biochemical changes in dentin modify the refraction of light through the tooth and
thus changes its appearance. The discoloration of tooth can result because of
incomplete cleaning and shaping of the root canal system, the accumulation of
sealer, debris or filling materials left in the chamber.
Planning post-endodontic restoration procedure

Various studies of unsuccessful endodontic procedures have shown failures due to
inadequate restoration of the teeth. Restorative treatment of tooth depends upon
amount of remaining tooth structure, its functional need and need for the tooth as
abutment. After caries is removed and access cavity is prepared, the
post-endodontic restoration can be planned following the complete visualization of
the tooth.
(A) For anterior teeth:
Not all endodontically treated teeth need posts.

1- Most teeth with healthy remaining tooth can be restored by direct filling of the
access cavity usually tooth composite resins or glass ionomer cements.
Composite resin is the most appropriate material for restoring the access
cavity, because of its physical properties and a high quality surface finish,
together with a good seal achieved by acid-etching enamel. Care must be
taken to ensure that the root canal filling is removed from the cro wn of the
tooth to prevent the discoloration of the dentine due to endodontic sealers
containing eugenol.
2- For devitalized, discolored anterior teeth where more than half of the coronal
structure is intact, the preferred treatment should be bleaching or/and composite
or porcelain laminate veneers rather than the full coverage crowns or post and
core.
3- But if there is doubt regarding the adequacy of resistance form of the coronal
portion of the tooth for any restoration, then in such cases post and core is
indicated.
Tooth reinforcement:
There is no indication for the placement of a post within the root canal of a
relatively intact anterior tooth. The idea that the post can reinforce a tooth and
therefore protect against fracture has been shown to be untrue.
With the increased range of adhesive techniques available for restoring anterior
teeth, together with the lack of benefit of placing posts, give rise for a conservative
approach to the restoration of even extensively damaged root-canal-treated anterior
teeth.
Once it is accepted that posts do not strengthen teeth, there are good reasons to
avoid post placement in anterior teeth, particularly in younger patients where wide
root canals mean that there is little radicular dentine.
Anterior teeth without posts:

Sometime crown is necessary for a root-canal-treated anterior tooth but it is
certainly not necessary for post placement. For example when anterior teeth are
in normal occlusion, with enough palatal wall of dentine in maxillary anteriors or
the labial wall for mandibular anteriors which are important in providing
retention and resistance form.
The labiolingual dimension of mandibular incisors at the junction between the
crown and the root is small. With the combination of the loss of tooth structure
by the endodontic access cavity and the crown preparation generally removes
large percentage of the coronal tissue that very often a post will be necessary to
support a crown.
While maxillary anterior teeth are larger at the amelo-cemental junction. So
when the endodontic access cavity is sited carefully, with sufficient coronal
tissue remaining after crown preparation to allow the dentine core to support the
crown without the need for post placement.
B) For Posterior Teeth:

Since posterior teeth arc subjected to greater loading; than anterior teeth, these
should be treated differently. Also the morphology of posterior teeth is such that the
cusps can be wedged apart, which make them more susceptible to fracture.
1. If there are no proximal fillings, caries or unsupported cusps or strong facets, the
access cavity of posterior teeth can be easily
restored with amalgam or high strength
posterior composites.
2. If there moderate damage of posterior teeth
having at least minimum of one sound cusp, the
choice of restoration can be:
*Amalgam: Coronal-radicular core which is finally
restored with cast restoration
*Pin retained restorations
*Onlay
*Prosthetic crown
3. In case there is presence of severally damaged clinical crown with no remaining
cusps, the root canal used as space for intraradicular retention.
Conservative restoration of posterior teeth…

The wider the isthmus in a class II cavity, the
lower the resistance to fracture of the tooth. The
endodontically treated posterior tooth has lost the
roof of its pulp chamber and both coronal and
Radicular dentine. Added to this is the loss of
dentine associated with previous restoration.
Posterior teeth with root canal treatment require
restorations that will:
1) Preserve and/or protect remaining tooth structure.
2) Maintain occlusal stability.
The protecting of the remaining tooth structure are obvious, while the stability in
the occlusion is necessary to control the loads and prevent the damage of the tooth
and restoration.
Adhesive restorations for posterior root-filled teeth…

The endodontic access cavity in a posterior tooth not only removes the roof of the
pulp chamber but also creates a wide occlusal isthmus. Consequently, even if both
marginal ridges remain intact, the tooth must be considered at some risk from
fracture.
Much interest has centered in recent years on the ability of adhesive posterior
restorations to reinforce the remaining tooth structure. Composite resin placed with
an etched enamel technique increases the resistance to fracture of root-filled teeth
compared with non-adhesive restorations.
It can be argued that composite resin represents the best option when restoring
small cavities in the occlusal surfaces of posterior teeth, because the operative
field can generally be well controlled, the margins of the cavity are all in enamel
and a small restoration is not often required to replace a large number of occlusal
contacts.
But difficulties raised by using composite resin in larger cavities in posterior
teeth, especially those involving proximal surfaces. Because of difficulties in
isolation, control of matrices and the resultant proximal contact and form are
often difficult. Such restorations present problems when large because the
ultimate shaping and finishing of the occlusal surface have to be carried out with
rotary instruments. Trying to produce precise occlusal functional form. Another
factor affecting stability in the occlusion will be the resistance of the composite
resin to wear and also its effect on the wear of opposing teeth. There is evidence
to suggest that the further posterior the restoration in the mouth, the more it is
likely to wear.
Crown restorations for endodontically treated tooth:

A cast restoration can provides a conservative method for restoring and
protecting the extensively damaged root-treated posterior tooth. It is important not
to use a full ceramic-coverage metal-ceramic restoration, because heavy tooth
reduction is done to create the necessary room for the restoration lead to remove
the remaining coronal dentine.
The use of two three-quarter gold veneers on a maxillary premolar and molar,
which appear unaesthetic. This treatment decision was made after discussion
with the patient because the only substantial wall of tooth structure remaining in
each tooth was the buccal cusp.
The preparation for full-coverage metal-ceramic restorations need full buccal
reduction and loss/weakening of cusps. This worsened the long-term prognosis
for the teeth.
The use of partial and full-coverage restorations in yellow gold remains an
appropriate method for the restoration of endodontically treated posterior teeth
where there is a reasonable quantity of coronal dentine remaining.
The benefit of crowns in preventing fracture of root-treated posterior teeth has
been emphasized in study where an incidence of posterior tooth fracture of
nearly 60% was recorded when crowns were not used.
Position of the preparation margin:

Whatever core material is used, the position of the axial margins of the crown is
important as it is a site of stress concentration. This is also likely to be true for the
margin of core. One aim of the crown preparation must be to position the margin on
sound tooth structure so that the stresses received by the crown are transferred to the
root of the tooth; this helps to minimize the loads on the core.
When different cores were tested on extracted root without final crowns covering
them, there were quite marked differences in their resistance to failure. However,
when the tests were repeated with final crowns in place, and their margins were
extended 2mm onto sound tooth structure, there was little difference between
different core materials used in tested groups.
The margins of the final preparation should extend well onto sound tooth structure.
This may sometimes require that a surgical crown-lengthening procedure is carried
out after placement of the core prior to crown preparation to provide visible tooth
structure apical to the margins of the core.
Post (dowels)
It is rigid restorative material placed in the root of non-vital tooth. It extends
coronally to provide retention for the core material that supports the crown.
Core
Core is the supra-gingival portion that replaces the missing coronal
tooth structure and forms the center of new restoration. Basically it
act as a miniature crown.
Features Evaluated before going for Post and Core:

*Restorability of the tooth
*Role of tooth in the month
*Periodontal considerations
*Functional loading
Requirements of a Tooth to Accept a Post and Core:

*Optimal apical seal
*Absence of fistula or exudate
*Absence of active inflammation
*No sensitivity to percussion
*Absence of associated periodontal disease
*Sufficient bone support around the root.
*Sound tooth structure coronal to alveolar crest
*Absence of any fracture of root.
Conditions where post should not be given:

1. Any sign of endodontic failures are evident, i.e. tooth exhibits
•Poor apical seal and poor quality obturation
•Active inflammation
•Presence of fistula or sinus
• Tender on percussion
2. If adequate retention of core can be achieved by natural undercuts of crown.
3. If there are horizontal cracks in the coronal portion of the teeth.
4. When tooth is subjected to excursive occlusal stresses such as when there is
presence of lateral stresses of bruxism or heavy incisal guidance.
Finally the timing the restorative procedure:

How long to wait after root canal treatment before placing the final restoration. There
is no set answer to this.
The satisfactory result of the final radiograph and the absence of symptoms, and the
pulp had previously been vital; the placement of the final restoration can be proceeding
immediately.
In contrast, if there had been an apical radiolucency prior to treatment associated with
an unsatisfactory root canal filling, the placement of a satisfactory root canal filling
would not give the same chance of success. In such cases, it would be sensible to delay
the final restoration until evidence of periradicular healing is seen radiographically.
Because further endodontic treatment is more complicated. For example, the
placement of a post in the palatal root of a maxillary molar makes further root canal
treatment difficult. That is why the decision is taken to wait for evidence of healing
little will be seen radiographically. During this time, the remaining tooth structure
must be protected by an adequate temporary restoration which must also be capable of
preventing coronal leakage.
Endodontics
Restoration of Endodontically Treated Teeth (Part 2)

Post & Core
Post (dowels)
It is relatively rigid restorative material placed in the root of non -vital tooth. It
extends coronally to anchor the core material which supports the crown.
Post mainly serves two functions:

1-Helps in retaining the core
2-Helps in favorable distribution of the stresses inside the radicular portion of teeth .
Earlier it was believed that posts strengthen or reinforce the teeth but it has been
shown by various studies that posts actually weaken the tooth and increase the risk of
root fracture. It has been suggested that endodontically treated teeth are more brittle
and may fracture more easily than vital teeth. Subsequently post space preparation or
placement of post can further weaken the root and may lead to root fracture.
Therefore, a post should be used only when there is insufficient tooth structure
remaining to support the final restoration. In other words, the main function of post is
retention of the core to support the coronal restoration.
Factors To Be Considered While Planning Post and Core

A. Retention and the Resistance Form
Post retention refers to the ability of post to resist dislodging forces.
Post resistance refers to the ability ot post and the tooth to withstand the lateral and
rotational forces.
*Post length
There are many guidelines available as suggested by various authors regarding the
post length. It is obvious that longer the post in the canal, more retentive it is. But
increased length also increases risk of root fracture and perforation. Generally, it is
accepted that apical 3-5 mm of gutta-percha must be preserved to maintain the ap ical
seal.
Accepted Guidelines for determining length Include:

1-Post should be equal to clinical crown length.
2-Post should be equal to one half to two thirds of the length of the remaining root.
3-Post should be end half way between the crestal bone and the root apex.
4-Post should be as long as possible without disturbing the apical seal.
Since root anatomy varies from tooth to tooth, so post space should be evaluated and
planned accordingly.
With molars, posts should be placed in the primary roots (palatal root of maxillar y
molars and distal roots of mandibular molars) and should not be extended more
than 7 mm apical to the origin of the root canal from the base of the pulp chamber.
Extension beyond this length can lead to root perforation or only very thin areas of
remaining tooth structure
*Post Diameter
It has been seen that post diameter has little difference in the retention of p ost, but
increase in post diameter increases the risk of root fracture.
Presently three different philosophies have been given regarding t he p ost diameter,
these are:
1-The Conservationist
It suggests the narrowest diameter that allows the
fabrication of a post to the desired length. It allows
minimal instrumentation of the canal for p ost space
preparation. According to this, teeth with smaller
dowels/post exhibit greater resistance to fracture.
2-The Preservationist
It advocates that at least 1mm of sound dentin should
be maintained circumferentially to resist the fracture.
3-The Proportionist
This advocates that post width should not exceed one
third of the root width at its narrowest dimensions to
resist fracture. The guideline for determining
appropriate diameter of post involves mesiodistal
width of the roots.
* Post design
Posts or dowels can be generally classified as cement/bonded posts or threaded
posts. Cemented posts depend on their close proximity to the prepared dentin walls
and the cementing medium. Examples are custom-cast posts and cores and a variety
of prefabricated designs.
The prefabricated designs include parallel-sided metal posts and/or different types of
threaded posts. Threaded posts depend primarily on engaging the tooth either through
threads formed in the dentin as the post is screwed into the root or through thread s
previously “tapped” into the dentin (e.g., the Kurer post). Examples of threaded posts
include the Kurer post, the Dentatus post, and the Flexi-Post.
Recently, posts made of carbon fiber (C-Post, Aesthetic Post, and Light Post, Bisco,
Inc), ceramic materials, and fiber-reinforced polymers have been introduced.
Research indicates that these new carbon fiber posts possess adequate rigidity and
they do not produce tooth fracture and have been shown to be clinically successful. It
is reported that carbon fiber posts can be removed from the tooth. Ceramic posts have
very high flexural strengths and are very hard.
For teeth with large and/or round roots with little remaining root thickness after
endodontic treatment is completed, either a prefabricated post or custom cast post can
be used. If root preparation is required to accommodate a prefabricated (round) p ost
form will reduce dentin thickness to less than a 1 mm, then a custom-cast post
becomes the safest type of post.
Various types of post designs are available in the market. The post can be:
• Tapered, smooth sided—Least retentive
• Tapered, serrated type
• Parallel smooth sided
• Parallel serrated type
• Tapered notached
• Parallel threaded type
• Parallel! notched type
Generally parallel sided are more retentive than tapered ones. Threaded posts are
more retentive than cemented ones.
*Luting agents
Commonly used dental cements for luting the posts are zinc phosphate,
polycarboxylate, glass ionomer cement, resin based composite and hybrid of resin
and ionomer. Among these, zinc phosphate has shown the longest history of success.
GIC is also one of the frequently used Luting agent.
Resin based composites are becoming increasingly popular because of its potential to
bond to the dentin. But bonding resin cement to dentin wall of root canal sp ace must
be done carefully to improve bonding and minimize microleakage.
*Canal shape
Since the most common shape of canal is ovoid and prefabricated p osts commonly
used are parallel in mature the majority of prefabricated posts are unlikely to adapt
well along their entire interface with canal walls. knowing the root anatomy of
different teeth is important before starting canal preparation for post installation . To
determine the appropriate post length and width to avoid root p erforation one must
consider condition such as root taper, proximal root invagination, root curvature and
angle of the crown to the root during preparation of the post space. For this good
quality of radiographs provide needed information.
*Position of the tooth in the dental arch

Location of the tooth in denial arch also affects the post retention, for example
maxillary anterior region is at high risk for failure because of effect of comp ressive,
tensile, shearing and torqueing forces specially at the post-dentin interface. If all
factors are equal, then post of posterior teeth tends to be more retentive than anterior
ones.
B. Preservation of the Tooth Structure

One should try to preserve maximum of the coronal and radicular tooth structure
whenever possible. Minimal removal of additional radicular dentin for post space
preparation should be the criteria. Further enlargement for p osts only weakens the
tooth. Minimal enlargement of post space mean a post must be made of a strong
material than can withstand functional and Para-functional forces.
So factors Affecting Clinical Longevity of Post and Core

*Magnitude and direction of force.
*Tooth type
*Thickness at remaining dentin
*Post selection
Preparation of the Canal Space and the tooth:

1. Plan for the length and diameter of the post to the tooth
type and using proper radiograph.
2. Remove the gutta-percha filling. Whenever gutta-percha
is removed immediate after obturation as not to disturb
the apical seal. Gutta- percha can be removed using the
hot endodontic instrument, rotary instrument, chemical
methods or by use of solvents.
3. Prepare the canal space using Gates-Glidden drills or
peeso reamer. The canal space enlargement depends on
type of the post. If it is custom made, the main
requirement is minimal space preparation without undercuts.
For prefabricated post, generally specific penetration drills
for each system are supplied for canal preparation.
4. Following the preparation of canal space, preparation of
coronal tooth structure should be prepared in the same
manner as if an intact crown irrespective of the remaining
tooth structure.
5. Remove all the un supported tooth structure.
6. Place an antirotational notch with the help of cylindrical
diamond or carbide bur. This is done to provide the
antirotational stability.
7. Ferrule effect is provided thereafter. The remaining coronal
tooth structure is sloped to buccal and lingual surfaces so as
to provide a collar around the occlusal circumference of the
preparation. This gives to rise to 360° ferrule effect. Ferrule
ensures that the final restoration encircles the tooth ap ical to
the core and rests on sound tooth structure. It is also presents
the vertical root fracture by posts.
8. Finally eliminate all the sharp angles, undercuts and establish
a smooth finish line.
Core
Core is the supra-gingival portion that replaces the missing coronal tooth structure
and forms the center of new restoration. Basically, it acts as a miniature crown.
Cores for crown restorations:

The loss of coronal tissue by previous restorations and root canal treatment core is
required to support the final crown. There is a need to provide adequate retention for
the core. The general principles of core retention is the same way as for vital teeth, by
providing boxes and other retentive features within the bulk of dentine.
There are no indications for the use of self-threading pins in endodontically treated
teeth. Because of, inadequate bulk of dentine for placing the pins, also self-threading
pins create stresses in both the tooth structure and the core, that cause crack
propagation, which lead to increase in tooth fracture or loss of core retention.
If the use of pin is necessary, the cemented type should be used (the p in should be
retained by a cement lute and they need to extend 4mm into dentine to provide
adequate retention, which can make them difficult to place safely).
Amalgam dowel core:

This technique works well in posterior teeth where a minimum of one cusp with a
good dentine base remains even after following crown preparation, because if no
cuspal dentine remains there is a danger that the amalgam core could fracture at
the level of the roof of the pulp chamber.
The following points should be noted:
1) All the root canal filling material must be removed from the pulp chamber.
2) Gutta-percha is removed from the coronal 2-3mm of the root canals using a
Gates-Glidden drill, the dimensions should
same size or slightly larger than the coronal
aspect of the root canal. This prevents the
Gates-Glidden drill from penetrating the
mass of gutta-percha and tearing it from the
root canal. The Gates-Glidden drill should
be run at low speed and high torque to melt
the gutta-percha ahead of the blunt tip.
3) Extension of the amalgam more than the
recommended 2-3mm will not improve the
retention of the core but will make later
removal of the amalgam much more difficult
should root canal retreatment be required.
4) The retention and resistance form have been improved by the use of further
retentive features in the coronal aspect of the tooth. A groove has been placed in
dentine palatal to the access cavity and the features of the distal box have been
sharpened.
5) Condensation of the amalgam alloy into the coronal aspects of the root canals
requires appropriately sized amalgam condensers.
Choice of material:
Various core build ups materials available are:
*Dental amalgam
*Resin modified glass ionomers
*Composite resin
*Reinforced glass ionomer cement
The demands on the core vary depending on its size and also the loads it will receive.
When a large bulk of coronal dentine remains, the choice of core material is not
critical, but it becomes critical as the amount of dentine remaining decreases. The
critical point is when less than one wall of a posterior tooth remains. Under such
circumstances, both composite resin and cermets are risky choices.
Composite resin has always performed well in tests in vitro of core materials, but
more recently concerns have been expressed about its dimensional and hydrolytic
stability. These have added to the clinical impression of large composite resin cores
tending to become loose beneath cast restorations.
Cermets, (glass ionomer cement derivatives), possess adhesive p roperties and this
provides good resistance to microleakage. However, retentive values are low -
approximately (25%) to those using composite resin on etched enamel. Cermets may
be very useful materials for small cores, their compressive and tensile strengths are
low compared with other core materials. They should be used with great caution
when the core is large.
Silver amalgam as a core material remains popular because of its physical properties.
In an interesting in vitro study testing extracted root-treated premolar teeth restored
with posts, cores of composite resin, cermet or amalgam, the results showed crowns
failure of 60% in the composite resin group, 90% in the cermet group and 30% in the
amalgam group, this failure can be overcome by using proper p lacement of Ferrule
effect.
It is often said that amalgam is not a practical core material as it cannot be prepared at
the same visit as it is placed. Using of fast-setting amalgam alloy, the bulk of the
initial preparation can be made with an amalgam carver and completed using a
turbine with light pressure under water spray.
Ideal Requirements for a Core Material:

*Compressive strength to resist intraoral forces
*Biocompatibility
*Ease of manipulation
*Flexure strength to present core dislodgement
*Ability to bond to tooth structure and post.
*Coefficient of thermal expansion similar dentin.
*Minimal water absorption
*Dimensionally stable
*No reaction with chemicals
*Low cost and Easily available
*Contrasting color to tooth structure except when used for anterior teeth.
Biomechanical criteria for evaluation of core materials:
Bonding
Resin composites > GJass ionomers > Amalgam
Strength
Amalgam > Resin composite > Glass ionomers
Ease of Use
Resin composites > Amalgam > Glass ionomers
Setting Time
Resin composite > Glass ionomers > Amalgam
Dimensional Stability
Amalgam > Glass ionomers > Composite resins
Following endodontic treatment, it is necessary to restore the original morphology
and function of the tooth which can be achieved by restoration of the
endodontically treated teeth. The restoration should begin at the earliest possible
moment because tooth exposed to oral conditions without optimal restoration
cannot resist the occlusal forces and oral bacteria for a long period which can
result in the treatment failure. Post endodontic restoration is an important
treatment cannot be achieved without adequate restoration after endodontic
treatment. Proper restoration of endodontically treated tooth begin with
understanding of their physical and biomechanical properties and anatomy.
Though various new materials have become available for past many years, yet the
basic concepts of restoring endodontically treated teeth remains the same.
endodontic
Diagnosis and treatment planning
Diagnosis:
There are many causes of facial pain and the differential diagnosis can be
both difficult and demanding. All the relevant information must be collected;
this includes a case history and the results of both a clinical examination and
diagnostic tests.
Case history:
The purpose of a case history is to discover whether the patient has any
general or local condition that might alter the normal course of treatment.
Medical history:
The clinician is responsible for taking a proper medical history from every
patient who presents for treatment. Any patient '' of record'' should be
questioned at each treatment visit to determine any changes in the patients
medical history or medications. A more through and complete update of the
patients medical history should be completed if the patient has not been seen
for over a year.
The clinician should evaluated a patients response to the health questionnaire
from two perspectives:
(1) those medical conditions and current medications that will necessitate
altering the manner in which dental care will be provided :
a-cardiovascular (eg: endocarditis, hypertension, unstable angina pectoris,
recent myocardial infraction etc……)
b-pulmonary (eg: asthma, tuberculosis)
c-hematologic (eg: diabetes mellitus, pregnancy, bleeding disorder, leukemia,
HIV and AIDS)
d-nurologic: (eg: cerebrovascular accident, anxiety, drug or alcohol abuse
etc….)
(2) those medical conditions that may have oral manifestations or mimic
dental pathosis:
a- tuberculosis involvement of the cervical and submandibular lymphnod nodes
b- uncontrolled diabetes mellitus respond poorly to dental treatment and may
exhibit recurring abscesses in the oral cavity .
c- multiple myeloma can result in unexplained mobility of teeth.
1
d- acute maxillary sinusitis is a very common condition that may create
diagnostic confusion since it may mimic tooth pain in the maxillary posterior
quadrant.
If at the completion of a thorough dental examination, the subjective, objective,
clinical testing, and radiographic findings do not result in a diagnosis with an
obvious dental etiology, then consideration must be given that an existing
medical problem could be the true etiology. In such instances a consultation
with the patient's physician is always appropriate.
Patient’s complaints:
Listening carefully to the patient’s description of his/her symptoms can
provide invaluable information. It is quicker and more efficient to ask patients
specific, but not leading questions about their pain. Examples of the type of
questions which may be asked:
1) How long have you had the pain?

2) Do you know which tooth it is?
3) What initiates the pain?
4) How would you describe the pain?
Sharp or dull
Throbbing
Mild or severe
Localized or radiating
5) How long does the pain last?
6) When does it hurt most? During the day or at night?
7) Does anything relieve the pain?
In early pulpitis the patient can not localize the pain to a particular tooth
or jaw because the pulp does not contain any properioceptive nerve endings.
As the disease advances and the periapical region become involved, the
tooth will become tender and the properioceptive nerve ending in the
periodontal ligament are stimulated.
Clinical examination:
A clinical examination of the patient is carried out after the case history
has been completed. The temptation to start treatment on a tooth without
examining the remaining dentition must be resisted.
Extra-oral examination:
The patient’s face and neck are examined and any swelling, tender areas,
lymphadenopathy, or extra-oral sinuses noted.
2
Intra-oral examination:
An assessment of the patient’s general dental state is made:
1) Standard of oral hygiene.
2) Amount and quality of restorative work.
3) Prevalence of caries.
4) Missing and unopposed teeth.
5) General periodontal condition.
6) Presence of soft or hard swellings.
7) Presence of any sinus tracts.
8) Discolored teeth.
9) Tooth wear and facets.
10) Intraoral sinus tracts: occasionally a
chronic endodontics infection will drain
through an intraoral communication to the
gingival surface known as a sinus tract. this
pathway, which is some time lined by
epithelium, extends directly from the source
of infection to a surface opening, on the
attached gingival surface.
Diagnostic tests:
No single test, however positive the result, is sufficient to make a firm
diagnosis of reversible or irreversible pulpitis. There is a general rule that
before drilling into a pulp chamber there should be two independent positive
diagnostic tests.
-Palpation:
The tissues overlying the apices of any suspect
teeth are palpated to locate tender areas. The site and size
of any soft or hard swellings are noted and examined for
fluctuation and crepitus.
- Percussion:
Gentle tapping with a finger both laterally and
vertically on a tooth is sufficient to elicit any tenderness.
It is not necessary to strike the tooth with a mirror
handle, as this invites a false positive reaction from the
patient.
3
- Mobility:
The mobility of a tooth is tested by placing a
finger on either side of the crown and pushing with one
finger while assessing any movement with the other.
Mobility may be graded as:
1) Slight (normal).
2) Moderate.
3) Excessive movement in a lateral or mesiodistal
direction combined with a vertical displacement
in the alveolus.
- Radiography:
In all endodontic cases, a good intra-oral parallel
radiograph of the root and periapical region is
mandatory. Radiography is the most reliable of all the
diagnostic tests and provides the most valuable
information.
- Pulp testing:
The electric pulp tester is an instrument which
uses gradations of electric current to excite a response
from the nervous tissue within the pulp. Pulp testers
should only be used to assess vital or non vital pulps,
they do not quantify disease, nor do they measure health
and should not be used to judge the degree of pulpal
disease.
Thermal pulp testing:
This involves applying either heat or cold to a tooth, but neither test is
particularly reliable and may produce either false positive or false negative
results.
Heat:
There are several different methods of applying heat to a tooth. The tip of a
gutta-percha stick may be heated in a flame and applied t a tooth. It’s advisable
to coat the tooth with Vaseline to prevent the gutta-percha sticking and causing
unnecessary pain to the patient. Another method is to use the heat generated
from wheel in a standard hand-piece.
Cold:
An ethyl chloride spray on a pledged f cotton wool or an ice stick may be
applied to the suspect tooth. Ice stick is made by filling the plastic covers from
a hypodermal needle with water and placing in a refrigerator.
4
Local anesthetic:
In cases where the patient can not locate the pain and the thermal test is
negative, a reaction may be obtained by asking the patient to sip hot water from
a cup. The patient is instructed to hold the water first against the mandibular
teeth on one side and then by tilting the head, to include the maxillary teeth. If a
reaction occurs, an intraligamental injection may be given to anaesthetize the
suspect tooth and hot water is then again applied to the area, if there is no
reaction, the pulpitis tooth has been identified.
- Wooden stick:
If a patient complains of pain on chewing and there is no evidence of
periapical inflammation, an incomplete fracture of the tooth may be suspected.
Biting on a wood stick in these cases can elicit pain, usually on release of biting
pressure.
- Fiber optic light:

A powerful light can be used for trans-illuminating teeth to show
interproximal caries, fracture, opacity, or discoloration. To carry out the test,
the dental light is turned off and the fiber-optic light placed against the tooth at
the gingival margin and the beam directed through the tooth. If the crown of the
tooth is fractured, the light will pass through the tooth until it strikes the stain
lying in the fracture line, the tooth beyond the fracture will appear darker.
- cutting a test cavity:

When other tests have given an indeterminate result, a test cavity may be
cut in a tooth which is believed to be pulpless. In the author’s opinion, this test
can be unreliable as the patient may give a positive response although the pulp
is necrotic. This is because nerve tissue can continue to conduct impulses for
some time in the absence of a blood supply.
Treatment planning:
Having taken the case history and carried out the relevant diagnostic
tests, the patient’s treatment is then planned. The type of endodontic treatment
chosen must take into account the patient’s medical condition and general
dental state.
Indications for endodontics:

All teeth with pulpal or periapical pathology are candidates for
endodontics. There also situations where elective endodontics is the
treatment of choice.
5
- Post space: a vital tooth may have insufficient tooth
substance to retain a jacket crown so the tooth may be
root-treated and a post crown fitted.
- Overdenture: decoronated teeth retained in the arch to

preserve alveolar bone must be root-treated.
- Teeth with doubtful pulps: root treatment should be

considered for any tooth with doubtful vitality if it requires
an extensive restoration, particularly if it is to be a bridge abutment.
- Risk of exposure: preparing teeth for crowning in order to align them in

the dental arch can risk traumatic exposure. In some cases these teeth
should be electively root-treated.
- Periodontal disease: in multi-rooted teeth there may be deep pocketing

associated with one root or the furcation. The possibility of elective
devitalization following the resection of a root should be considered.
- Pulpal sclerosis following trauma: review periapical radiographs should

be taken following trauma. If progressive narrowing of the pulp space is
seen due to secondary dentine, elective endodontics may be considered
while the coronal portion of root canal is still patent. This may
occasionally apply after a pulpotomy has been carried out.
Contra-indications to endodontics:
The medical conditions which require special precautions prior to
endodontic treatment have already been listed. There are, however, other
conditions both general and local, which may contra-indicate endodontics.
General:
- Inadequate access: a patient with restricted opening or a small mouth
may not allow sufficient access for endodontic treatment. A rough guide
is that it must be possible to place two fingers between the mandibular
and maxillary incisor teeth so that there is good visual access to the areas
to be treated. An assessment for posterior endodontic surgery may be
made by retracting the cheek with a finger. If the operation site can be
seen directly with ease, then the access is sufficient.
- Poor oral hygiene: endodontics should not be carried out unless the
patient is able to maintain his/her mouth in a healthy state or can be
taught to do so.
6
- Patient’s general medical condition: the patient’s physical or mental
condition due to, for example, a chronic debilitating disease, or old age,
may preclude endodontic treatment. Similarly, the patient at high risk to
infective endocarditis, for example one who has had a previous attack,
may not be considered suitable for complex endodontic therapy.
- Patient’s attitude: unless the patient is sufficiently well motivated, a
simpler form of treatment is advised.
Local:
- Tooth not restorable: it must be possible following endodontic
treatment, to restore the tooth to health and function. The finishing line
of the restoration must be supracrestal and preferably supragingival.
- Insufficient periodontal support: provided the tooth is functional and
the attachment apparatus healthy, or can be made so, endodontic
treatment may be carried out.
- Non-strategic tooth: extraction should be considered rather than
endodontic treatment for unopposed and non-functional teeth.
- Root fractures: in complete fractures of the root
have a poor prognosis if the fracture line
communicates with the oral cavity as it becomes
infected. For this reason, vertical fractures will
often require extraction of the tooth while
horizontal root fractures have a more favorable
prognosis.
- Massive internal or external resorption: both types of restoration may

eventually lead to pathological fracture of the tooth. Internal resorption
ceases immediately the pulp is removed and, provided the tooth is
sufficiently strong, it may be retained.
- Bizarre anatomy: exceptionally curved roots, dilacerated teeth, and

congenital palatal grooves may all present considerable difficulties if
root canal treatment is attempted. In addition, any unusual anatomical
features related to the roots of the teeth should be noted as these may
affect prognosis.
Re-root treatment:
One problem confronts the general dental practitioner is to decide
whether an inadequate root treatment requires replacement. The questions the
operator should consider are:
1) Is there any evidence that the old root filling has failed?
a- Symptoms from the tooth.
7
b- Radiolucent area is still present or has increased in size.
c- Presence of sinus tract.
2) Does the crown of the tooth need restoring?
3) Is there any obvious fault with the present root filling which could lead
to failure?
The final decision by the operator on the treatment plan for a patient will
be governed by the level of his/her own skill and knowledge. General dental
practitioner can not become experts in all fields of dentistry and should learn to
be aware of their own limitations. The treatment plan proposed should be one
which the operator is confident he/she can carry out to a high standard.

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Endodontics

The re-emergence of endodontics as a respectable branch of dental

Lec.2 Dr. Iman Mohammed

Basic instrumentation in Endodontics:-

 Endodontic locking plier:-

When placing the stop on the instrument, it’s important to avoid

Lec:3 Dr. Iman Mohammed

A- K-file B- K-Flex file C- Flex-o-file

Hedstrom and Safety Hedstrom:-

New instrument design and technology:-

Canal Master U:-

* The No. 2 round bur is generally used in preparing mandibular

5) Once the orifices have been located, they should be

Principles of endodontic cavity preparation:-

Endodontic coronal cavity preparation:-

Endodontic Radicular cavity preparation:-

Principle I: Outline form

Principle II: - convenience form

2- direct access to the apical foramen:-

3- Extension to accommodate filling techniques:-

4- Complete authority over the enlarging instrument:-

Principle III: - removal of the remaining carious dentin and defective

Principle IV: - toilet of the cavity

Access opening of anterior teeth:-

A- Entrance is always gained through the

B- Initial entrance is prepared with a round-

C- Convenience extension toward the incisal

D- The preliminary cavity outline is funneled

E- A surgical length No.2 or 4 round burs in a

F- Once the pulp chamber has been penetrated,

G- Once the orifice(s) has been identified and confirmed, the

H- Occasionally, a No.1 or 2 round bur must be used laterally

J- Cavity preparations in "adult" teeth, with the chamber

Errors in cavity preparation:-

B- A regular-length No.2 or 4 round bur

C- An endodontic explorer is used to locate

F-Final preparation should

G-Outline form of final preparation will be identical for

Errors in cavity preparation:-

1 1 23mm One canal 100% Straight 75%

Distal curve 53%,

3 3 Distal curve 32%,

One canal/ one foramen

Straight 68%, distal

Two canals/ two

One canal/one foramen

Access opening of posterior teeth:-

B- According to the size of the chamber, a regular-length

D- Again, wording at slow speed from

E- In posterior teeth the internal impediments are the cervical

B- According to the size of the chamber, a

D- Again, working at slow speed from the inside to outside, a

G- "Square" outline form reflects the anatomy of the pulp

Errors in cavity preparation of posterior teeth:-

4) Inadequate vertical preparation related to failure to

Mesiobuccal 3 canals 41% One canal/one 41%

Determination of working length

Anatomic consideration and terminology:-

Methods of determining working length:-