GOOD

AFTERNOON

IMPLANT LOADING
PROTOCOLS AND
THEIR RATIONALE

Sushant Rohilla
Junior Resident III

INTRODUCTION
Predictable formation of a direct bone to
implant interface is a basic treatment goal
in implant dentistry.
The TWO STAGE SURGICAL PROTOCOL for
implant placement and prosthodontic
rehabilitation as established by Branemark
et al. (1977) to accomplish osseointegration
consist of several prerequisites, which
include -

Countersinking of the implant below

the crestal bone.

Obtaining and maintaining a soft-tissue

covering over the implant for 3 to 6
months.

Maintaining a minimally loaded

environment for 3 to 6 months.

The primary reasons cited for submerged,

countersunk surgical approach to
implant placement were
To reduce and minimize the risk of
bacterial infection,
To prevent the apical migration of the
oral epithelium, and
To minimize the early implant loading.

Branemark and several other workers

achieved predictable long term, clinical
rigid fixation with this protocol both in
partially and completely edentulous
patients.
However there are some drawbacks
related to this type of classical loading
protocol .

DRAWBACKS OF
BRANEMARKS
LOADING PROTOCOL

 Discomfort and inconvenience of second

stage surgery.
Extended treatment time.
It was observed that even if an initial direct
bone to implant interface has been
established and confirmed at post healing
stage II surgery, the implant is most at risk for
failure or crestal bone loss within the FIRST
YEAR.

If the treatment provides adequate support,the

three most common causes of early prosthetic
related implant failure are
Non passive superstructure,
Partially unretained restorations, and
Loading of the implant support system beyond
the strength of the bone to implant interface.

Challenging the very concept of

Branemark , came two different protocols
for loading of implant- bone interface

PROGRESSIVE IMPLANT LOADING

AND
IMMEDIATE IMPLANT LOADING
PROTOCOLS

PROGRESSIVE IMPLANT LOADING

Misch (1980) proposed the concept of
progressive or gradual bone loading
during prosthetic reconstruction to
decrease the crestal bone loss and early
implant failure in endosteal implants.
Progressive bone loading is more critical for
lesser bone densities because they are
several times weaker than the those with
significant cortical bone.

Parafunction, cantilever and other stress

magnifiers can increase the force applied to the
prosthesis and their shear components and
cause bone microfracture or microstrains in the
pathologic loading zone .
The ULTIMATE AIM OF PROGRESSIVE BONE
LOADING is to
increase the density of bone,
decrease the risk of implant-bone failure
decrease crestal bone loss

BONE DENSITY IN RELATION TO PROGRESSIVE

LOADING

As per the WOLFFS LAW ( 1892)

Every change in the form or function of
bones or of their function alone is
followed by certain definite changes in
their internal architecture and equally
definite alterations in the external
conformation, in accordance with
mathematical laws.

Generalized loss of bone volume and density

occurs in regions of tooth loss. The decrease in
density is related to Length of edentulism
Original density of the bone
Muscles attachments
Bone flexure and torsion
Parafunction
Hormonal influences
Systemic conditions

Bone responds to hormonal and

biomechanical regulation and even in
conditions with high demands calcium,
functional loading can compete and
maintain bone mass (Marks et al.1988).
Bone also responds to stress if within
physiologically limits and exercise
prevents bone loss.

Frost showed that increase in bone mass is

related to strain applied to the bone . The
actual strain perceived by the bone tissue
initiates a chain reaction of events that
results in biological response .
BONE CELLS and EXTRACELLULAR MATRIX
compose the strain sensitive population.
Membrane deformation, intracellular action,
and extra-cellular action are proposed
cellular mechanisms.

Dynamic or cyclic loading is necessary for bone

remodeling.
Greater the rate of change of applied strain in
bone , the more bone formation is increased.
Lower magnitude for many cycles can
produce the same anabolic effect that a
greater magnitude force applied force will
produce if applied for shorter durations.

BONE IMPLANT INTERFACE

Functional loading of implants brings
biomechanical influences, which
greatly affects the bone maturation.
Bone density increase is primarily
reflective of the local stress factors and
endosteal implants are major methods
to alter the strain and increase the
bone density.

The ideal bone for the implant

prosthetic support is LAMELLAR
BONE, which is highly organized
but takes 1 year to mineralize
completely after surgical trauma
induced by the implants.

WOVEN BONE is the fastest and first

bone to form around implant interface,
however it is only partially
mineralized / organized and less able
to withstand full scale stresses.
At 16 weeks ( 4 months) after implant
placement, the bone is only 70%
mineralized and of woven bone nature.

The greatest stress around a rigidly

fixated implant occurs at the bone
crest.
According to Manz, the crestal bone
loss after successful bone
integration was related to directly
to the bone density.

As bone is loaded physiologically , a gradual

increase in loads during prosthesis
fabrication stimulates an increase in bone
density.
It was further observed that softer bones
lost more of crestal bone , and increasing
the bone implant interface density reduce
the crestal bone loss.

PROGRESSIVE LOADING PROTOCOL

It is well agreed fact that fewer the
no. of implants, softer the bone
type, and higher the risk factors
( eg. presence of cantilevers,
patient force factors, implant
position etc) , more critical will be
the progressive bone loading.

 Full arch prosthesis with little or no

cantilever , adequate implant no,
position, and size rarely require
progressive implant loading.
The favorable biomechanics of an arch
are compatible with immediate loading
protocol.

The principles of progressive loading are demonstrated

best in cement retained prosthesis and are least
applicable for screw retained bar of a mandibular
removable prosthesis ( RP-5).
Screw retained prosthesis are difficult to load
progressively becausea) Transitional prosthesis is movable during fabrication
phase.
b) Most of the forces placed on to the implants are
generated a delivery due to non passive superstructure.
Generally longer healing time are suggested if force kevels
are greater

(a) TIME
Branemarks two stage protocol separates initial
implant placement and stage II uncovery by 3 to 8
months.
In Progressive loading protocol usually five major
prosthodontic appointments are made and are
separated by some specific time interval related to
bone density observed at the initial surgery.
In addition the dentist attempts to gradually increase
the loading to the implants at each prosthetic step.

 Macroscopic coarse trabecular bone heals

about 50% faster than dense cortical bone.
D1 bone heals slowest but is strongest and
has greater lamellar bone contact.
D3 and D4 bones are suggested to have
greater healing time ( 5 and 6 months resp.)
because of lesser bone contact and
decreased amount of cortical bone to
develop same levels of interface maturation.
So it further seems that progressive loading
is more critical of these type of bones.

b) DIET
The dentist controls the diet of the patient to
prevent overloading during the early phases of
the restorative process .
DURING THE INITIAL HEALING PHASE,
The dentist instructs the patient to avoid
chewing in the area of the implant placement.
Once uncovered, the implant connected to high
abutment is at greater risk of loading during
mastication.

 FROM THE INITIAL TRANSITIONAL

PROSTHESIS DELIVERY UNTIL INITIAL
DELIVERY OF THE FINAL PROSTHESIS
The patient is limited to soft diet.
Masticatory force limit is 10psi.
The soft diet not only minimizes the masticatory
force on the implants and thus overloading of
implants but also decrease the risk of
temporary restoration fracture or partially
uncemented restoration.

 AFTER THE INITIAL DELIVERY OF THE FINAL

PROSTHESIS ,
The patient may include slightly tougher diet (meat)
Masticatory force limit is 21 psi.
AFTER FINAL EVALUATION APPOINTMENT
The patient may include raw vegetables which
requires a masticatory force of 27 psi .
A NORMAL DIET IS PERMITTED ONLY AFTER EVALUATION
OF THE FINAL PROSTHESIS FUNCTION, OCCLUSION AND
PROPER CEMENTATION

c) OCCLUSAL MATERIAL
The occlusal material may be varied to load
the bone to implant interface gradiually.
During the initial steps t he implants has no
occlusal material over it .
At subsequent appointments, the dentist uses
acrylic as the occlusal material, with the
benefit of lower impact force than the metal or
porcelain.

 As a final restoration,either metal or porcelain

can be used.
If parafunction or cantilever length cause
concern relative to the amount of force on the
early implant-bone interface, the dentist may
extend the softer diet and acrylic restoration
phase several months. In this way, the bone
has a longer time to mineralize and organize to
accommodate the higher forces

d) OCCLUSION
The dentist gradually intensifies the occlusal
contacts during prosthesis fabrication.
No occlusal contacts are permitted in initial
healing
time ( step1).
The first transitional prosthesis ( step 2) is left
out of occlusion in partially edentulous and no
cantilever are made in transitional prosthesis of
edentulous patients

 At transitional prosthesis stage II appointment

(step 3),the occlusal contacts then are similar
to those of final restoration for areas supported
by implants, however occlusal contacts are
avoided on cantilever. The occlusal table is kept
narrow like in final restoration.
The occlusal contacts on final restoration
follows implant protected occlusion guidelines
and occlusal table is kept narrow.

e) PROSTHESIS DESIGN
DURING INITIAL HEALING PHASE
The dentist attempts to avoid any load on the
implants, including soft loads.
The FIRST TRANSITIONAL ACRYLIC RESTORATION
in partially edentulous patients has no occlusal
contacts and no cantilevers. The main purpose of this
is to splint the implants together, to reduce stress by
the mechanical advantage, and to have implants
sustain masticatory forces solely from chewing

 In the SECOND ACRYLIC TRANSTIONAL

RESTORATION occlusal contacts are placed on
the implants with occlusal tables similar to the
final restoration bust with no cantilever in nonesthetic regions.
In the FINAL RESTORATION, narrow occlusal
tables and cantilever are designed with occlusal
contacts following implant-protective occlusion
guidelines

 Fig 26-5

IMMEDIATE IMPLANT LOADIN

During the last 18 years several authors have
reported that root form implants may
osseointegrate, even though they extend above the
bone and through the soft tissues during early bone
remodelling.
This surgical approach has been called a ONE STAGE
or NONSUBMERGED IMPLANT PROCEDURE
because it eliminates the second stage implant
uncovering surgery.

 Immediate loading not only includes a non

submerged one stage surgery but actually loads
the implant with the provisional restoration at
the same appointment or shortly thereafter.
Immediate loading is not new but was the initial
protocol suggested with dental implants.

RATIONALE OF IMMEDIATE IMPLANT LOADING

The immediate load concept eliminates the second

stage surgery and thus the resultant discomfort
and inconvenience of , and the time required by
the surgery and suture removal process.
In addition splinted implants could decrease the
risk of overload to each implant because of
greater surface area and improved biomechanical
distribution .

 The patient does not need to wear e removable

restoration during initial bone healing which
greatly increases comfort, function , speech and
stability and enhances certain psychological
factors during transitional period.
Over the last few years several authors have
reported on immediate loading in completely
edentulous patients, with 95-100% success rate

a) SURGICAL TRAUMA
Surgical process of implant insertions causes
regional accelerated phenomenon of bone
repair around the implant interface.
As a consequence of surgical placement,
lamellar bone in preparation site becomes
woven bone of repair next to the implants.

 Woven bone forms at a rate upto 60 MICRONS

PER DAY as compared to lamellar bone which
forms at rate upto 10 MICRONS PER DAY.
At 16 weeks ( 4 months) the surrounding bone
is still only 70% mineralized and exhibits woven
bone as a component.

 The IMMEDIATE IMPLANT LOADING CONCEPT

challenges the conventional healing time of 3 to
6 months of no loading before the restoration of
the implant.
Often the risks of this procedure are perceived to
be during the first week after the implant
insertion surgery. In reality, the bone in the
macroscopic thread design is stronger on the day
of the implant placement compared with the 3
months later, since there is more mature lamellar
bone in the threads in the implant

Early cellular repair is triggered by the surgical

trauma and begins to form an increased
vascularization and repair process to the injured
bone.
Woven bone formation may start at 2nd week
after implant placement. And the bone implant
interface is at highest risk of overload failure at
3-5week after implant placement.

 Reduction of surgical trauma in an effective method

to have more vital bone at the implant- bone
interface
( Roberts1984, found 1 mm wide zone
of devitalized bone at interface) which reduces the
risk of immediate occlusal overload .
The main causes of surgical trauma are THERMAL
and MECHANICAL TRAUMA.

* Temperature next drill --- 38C to more than 41C

base line and required
34 to 58 seconds to
return
to baseline

 Drills with internal cooled system drill at higher

temperature than those with external irrigation.
Drill rpm of 2500 produce less heat than 2000
rpm, while 1250 rpm produced created most heat.
Factors related to heat production are- amount of bone prepared
- drill sharpness
- depth of osteotomy
- variation of cortical thickness
- temperature and solution chemistry of irrigatant.

 The implant bone interface will have a larger

zone of repair when the implant is significantly
compressed against the bone. Eg a self tapping
implant may cause greater bone remodeling
compared with a bone tap and implant
placement technique.
The implant should not be mobile at placement
but excessive stress should be avoided. For
immediate loading implant placement within
the bone is limited to 45-60 Ncm

 Reverse torque test of 20 Ncm is used to

evaluate the quality of bone and interface
fixation ( Sullivan 1996, Palti 2002).
If implant does not unthread at 20Ncm the
resistance indicates that the bone is of
sufficient density to consider immediate
loading.

b) BONE LOADING TRAUMA

Once the bone is loaded by an implant prosthesis,
the interface begins to remodel again but the
trigger now is STRAIN TRANSFER CAUSED BY
OCCLUSAL FUNCTION, rather than the trauma
of implant placement.
The woven bone thus formed may be called
REACTIVE WOVEN BONE , and the remodeling
is called BONE TURNOVER.
INTERFACE REMODELING RATE is the period of
time for the bone at implant interface to be
replaced with new bone

 When the surgical trauma is too great or the

mechanical trauma situation is too severe,
fibrous tissue may form rather bone, resulting
in clinical mobility.

FACTORS WHICH REDUCE RISK IN

IMMEDIATE LOADING PROTOCOL
The factors are
1. BONE MICROSTRAIN
2. INCREASED SURFACE AREA
a) implant no.
b) implant size
c) implant body design
d) implant surface condition

3. DECREASED FORCE CONDITION

a) patient conditions
b) occlusal load direction
c) implant position
4. MECHANICAL PROPERTIES OF THE BONE

1. BONE MICROSTRAIN
Microstrain levels 100 times less than ultimate strength of bone
may trigger a cellular response. The ideal microstrain for bone is
called PHYSIOLOGICAL / ADAPTED ZONE - 50 TO 1500 microstrain
and is IDEAL LOAD BEARING ZONE

 One goal for an immediate loaded implant/

prosthesis system is to decrease the risk of
occlusal overload and its resultant increase in
the remodeling rate of bone.
Under these conditions the surgical regional
acceleratory phenomenon may replace the
bone interface without the additional risk of
biomechanical overload.

 If occlusal overload is not managed it will result

in 1500 3000 microstrains that is mild
overload zone causing trauma from overload.
And will hamper the bone remodeling from
surgical trauma.. Laeding to bone being less
mineralized, less oraganized, weaker, and lower
mod. of elasticity.

2. INCREASED IMPLANT SURFACE AREA

a) IMPLANT NUMBER
When immediate loading protocol is used
increased no. of implants are of special
importance because- It increases the surface area
- Increases the success rate even if one or two
implants fail.
- Increases the retention of prosthesis
- Reduces the no. of pontics

 Often more implants are used in maxilla ( 8-10)

than mandible (5-9), which compensates for
less dense bone and increased directions of
force found in upper arch.

b) IMPLANT SIZE
Implant height is not an effective method to
decrease stress, as far as non-immediate implant
loading proto is considered, because it doesn't
address the problem in functional surface area
region of bone-implant interface, which is better
related to implant width and design
However because the implant is loaded before the
establishment of histologic interface and implant
height is important for initial stability of implant ,
IMPLANT HEIGHT IS MORE RELEVANT FOR
IMMEDIATE IMPLANT LOADING applications,
especially in softer bones.

c) IMPLANT BODY DESIGN

The implant design should be more specific for
immediate loading because the bone has not
had time to grow into recess or undercuts ,
attach to surface conditions before application
of occlusal load.

Threaded implants allow bone to be present in depth

of threads from the day of insertion as compared to
press fit design.

Greater the no. of threads, greater the

functional surface area at the time of
immediate load

Greater the thread depth greater the surface

area for immediate load applications

 Functional surface area of an implant may

affect the remodeling rate of the bone during
loading. An implant with less surface area have
more remodeling rate, and higher the
remodeling rate, weaker the bone interface.

Square threads show better resistance to torque tha

V shaped or reverse buttress design.

 TAPERED DESIGN PRESENTS

DISADVANTAGES FOR IMMEDIATE LOADING
APPLICATIONS
- They do not engage the bone physically as
nicely as parellel , reducing the intial fixation.
- Along with this they have lesser total surface
area, lesser thread depth and no.
- They engages lateral cortical plate to lesser
extent at the apical region, and any de-rotation
may lead to lesser fixation.

d) IMPLANT SURFACE CONDITION

Surface conditions the rate if the bone
contact, lamellar bone formation, and the
% of bone contact.
The surface condition that allows bone
formation in greatest percentage, higher
bone implant contact % with higher
mineralization rate, and fastest lamellar
bone formation would be of benefit to
immediate loading protocol.

 Hydroxypatite (HA) has been shown to have

these properties along with reduced rate of
bone remodeling during occlusal loading.
Hence if bone is not of ideal density (D4)
for immediate loading HA may decrease
risk of overload.

3. DECREASED FORCE CONDITION

The dentist should reduce the factors that
magnify the noxious effects of force factors in
terms of magnitude, duration ,type and direction

a) PATIENT FACTORS
Force factors increase the risk for immediate
loading.
Parafunction such as bruxism and clenching not
only leads to increased force but also the
duration , more horizontally directed forces.
.

Parafunction also increases the risk of abutment screw

loosening, unretained restoration, and restoration fracture ,
jeopardizing the load distribution on immediate loaded
implants

b) OCCLUSAL LOAD DIRECTION

Axial load maintains the lamellar bone and has lower
remodeling rate than horizontally directed loads.
Therefore cantilevers in posterior regions should be avoided
in immediate loaded implants transitional restorations

C) IMPLANT POSITION
Cross arch splinting is an effective design to reduce
stress to entire implant support system, especially
in completely edentulous patients rehabilitated
with immediate loading.
Mandible may be divided into three sections :
canine to canine area, and the bilateral posterior
sections.

In mandible cross splinting has been an issue of

debate because of flexion and torsion distal to
mental foramen, but clinical reports show that
acrylic resin transitional prosthesis can solve this
problem.
However final restoration must be made in three
sections described.

 Maxilla require more implant support than

mandible because or less dense bone and
direction of of forceoutside of the arch in all
eccentric movements.
Maxilla is divided in to 4 or 5 sections
depending on force conditions and arch
shape.
Minimum four sections are bilateral canine
regions and bilateral posterior regions.

 When force factors are high , the incisor region

is included along with the standard four sections.
At least one implant should be inserted into each
maxillary section and splinted together during
the immediate loading applications.

THANK
YOU