Definition:

These are pit and fissure type cavities

that involve the occlusal surfaces of
molars and premolars, the occlusal 2/3
of buccal and lingual surfaces of
molars, and the palatal pits in maxillary
anterior teeth.
 These are self-cleansable areas.
However, they may get involved by
caries due to their inherent defective
structure as areas of imperfect
coalescence of lobes of calcification of
these teeth. These areas are retentive
for food and thus invite caries.
These lesions are clinically
characterized by:

1. A small surface opening which may

remain unnoticed until the lesion
becomes of a considerable size.
2. A conical spread in both enamel and
dentin, with the bases of cones at the
Amelo-Dentinal Junction, "A. J.D."
3. Its rapid burrowing at the dento-enamel
junction. These lesions may involve one
or more surfaces and hence a simple or
compound cavity should be prepared.
 Simple occlusal cavities

Designing the Outline Form.

The outline form of a routine class I cavity

should describe a symmetrical design running
in sweeping curves along all pits, fissures, and
angular grooves between the cusps and with a
minimum width.
The mesial and distal margins are
placed midway between the
bottom of the proximal fossae and
the crest of the proximal ridges
and in a direction parallel to these
ridges.
 The mesial and distal wall
should have a slant or slight
divergence from the pulpal floor
outward to avoid undermining
the marginal ridges.
In a bucco-Iingual direction, the
cavity is extended just sufficient to
eliminate the defective and susceptible
tissues. The lingual and the buccal
wail should be parallel to the
respective tooth surface.
 It must be reemphasized that the
outline form for class 1 cavities
should be very conservative since
they involve cleansable areas.
 It is governed only by the extent of
caries in both enamel and dentin
and the amount of extension or need
to eliminate pits and fissures to
secure smooth margins.
 Obtaining the Resistance and
Retention Forms
 The resistance form here consists chiefly
of a pulpal wall parallel to the occlusal
plane with dentin walls at right angles
to it., i.e. Boxing the preparation.
 The form of this cavity provides
automatically for effective retention
and, therefore, no special retentive
features are required.
 Removal of Carious Dentin

 In small size cavities, the carious dentin

should have been removed during making
the cavity extensions.
 In moderately deep and deep cavities, the
carious dentin is peeled off carefully at the
sides using large spoon excavators, and then
scooped out in few and large pieces.
 Only light pressure in a direction parallel to
that of the pulp is utilized. This is continued
until a sound dentin floor is reached.
 Planning of Enamel Walls

The enamel walls of the cavity should be

finished free from any loose, short, or
undermined enamel, and trimmed to meet the
tooth surface at a right cavo-surface angle.
This may be done by sharp and regular-edged
chisels and hatchets, plane fissure burs,
stones, or sand-paper discs.
All sharp corners in enamel must be rounded,
as they may contain short enamel rods.
 Performing of the toilet of the
cavity

A sharp explorer is then used to check

the details of the prepared cavity and
to loosen the tooth debris which are
then blasted out with warm air.
 Operative Procedures

Armamentarium

High speed handpiece

Burs #330, 56
Hoe
Hatchet R&L
Wedel staedt chisel
 Procedure

The outline form is performed by first

gaining access through the enamel to
the carious dentin floor of the cavity
followed by making the necessary
cavity extensions.
 In case of initial carious lesions, access
is obtained by employing a small pear
but #330.
 In big carious lesions, access is obtained
easily by breaking down the undermined
enamel overlying the carious dentin,
using a suitable size chisel.
 In either case, access is started at the
most defective area of enamel, i.e., a
carious pit or fissure.
 The bur is held at a right angle to
the involved surface of, the tooth and
light pressure in an in-and-out
direction is exerted. Cutting is
continued until the amelo-dentinal
junction (A.D.J.) is reached.
 The necessary cavity extensions
through pits, fissures, and deep
developmental grooves are made using a
#330 pear bur held at right angle to the
surface of the tooth.

The bur is rotated, and carefully

introduced through the opening just
obtained, so that its weak corners do not
touch the enamel and get dulled.
With the bur seated in the cavity just
below the amelo-dential junction 1/z-1 mm.
gentle pressure is applied in the direction
of required extension.

During cutting, the bur should be kept

moving in-and-out of the cavity and at
right angle to the tooth surface. In this
way, the bur will undermine and lift the cut
enamel, and at the same time unclog itself.
Provision of ample resistance and
adequate retention through boxing of
the preparation could be obtained.

This is obtained by using a #56 fissure

bur held perpendicular to the surface
of the tooth. All the line angle in dentin
must be squared up hoe excavators.
 Buccal Pit Cavities

The outline of these cavities usually

describes a triangle with its base
faming the gingival wall and its sides
forming the mesial and distal walls.

The gingival wall is placed at or

slightly occlusal to the height of
contour of the tooth.
All walls are extended just enough
to eliminate defective enamel and
dentin.

The enamel walls are planed in the

direction of enamel rods and
perpendicular to the axial wall.
Hoe excavators are used to smooth the
axial wall and make it parallel with the
external surface of the tooth.

It should be re-emphasize that the

shape of the cavity will be governed by
the extension of caries, accordingly the
outline of these cavities may be a
rounded or oval in shape.
 Buccal and Lingual Extensions

In case of occluso-buccal and occluso-

lingual cavities extensions are made
through the fissures and towards the
respective surfaces.
The cutting is done in dentin at the
amelo-dntinal junction using a #56 bur
until the ocdusal ridge is undermined
and removed.
If the caries is still gingival to the
level of the pulpal seat, a step is
indicated: a #330 or 56 but is used
to cut the dentin at the amelo-
dentinal junction, applying
pressure in a gingival direction and
at the same time moving the bur
mesio-distally.
The enamel thus undermined, is
broken down with chisels.

Retention grooves are then cut in

dentin along the axio-mesial and axio-
distal line angles. The cavity walls and
margins are finished as previously
described.
In case of deeply-seated caries,
where removal of the carious
dentin will leave a round cavity
floor, flattening of which to obtain
the required resistance form, will
expose the pulp.
 The following technique is used:

a) The cavity floor is covered with

a sub base of calcium
hydroxide, followed by a base of
glass ionomer cement which
fills it to the routine cavity
depth.
b) A ledge is cut on the expense of
the buccal and lingual side
walls of the cavity for obtaining
the required resistance in sound
dentin.
 Principles Rationale

I. OUTLINE FORM – Angular irregularities in

Smooth flowing, the outline are
regular curves. susceptible to fracture
during condensation – a
smooth flowing outline is
easier to visualize and
carve following
condensation.
II. EXTENSIONS – Conservation of tooth
structure is the basis for all cavity preparations
in order to preserve the strength of the tooth.
However, sufficient extension of cavity
preparations is necessary to ensure access
(convenience form) for instrumentation, removal
of defective tooth structure, insertion and
finish of the restorative material, and
maintenance of the restoration (prevention).
 Principles Rationale
A. Extensions circumscribe:
1. Caries and eliminates defective
decalcifications tooth structure and
2. Enamel unsupported by eliminates areas (pits,
sound dentin fissures, etc.) which are
susceptible to recurrent
3. Pits and fossae caries and facilities oral
hygiene procedures
4. Major fissures and
(extension for
grooves
prevention).
5. Existing restorations
 Principles Rationale

B. Bucco – lingual extension

1. Extend fully in areas of to allow a smooth

buccal and lingual grooves tooth-restoration
to terminate on smooth margin to be created
surfaces. (easier to finish and
keep clean).
 Principles Rationale

2. Extend minimally in areas to preserve the

of triangular ridges strength and function
(optimal isthmus width is of the cups while
¼ intercuspal distance or eliminating susceptible
less) terminating on grooves or defective
smooth surfaces. tooth structure (must
be wide enough to allow
condensation).
 Principles Rationale
C. Mesio-distal extension

1. Stop short of the to preserve strength of

marginal ridge crest. marginal ridges.

to preserve a uniform bulk

2. Parallel the contour of
(strength) to the mariginal
the marginal ridge.
ridges.
 Principles Rationale

3. Groove extensions are to preserve strength of

kept narrow (mesio- cusps while eliminating
distally) where susceptible grooves
possible (consistent and/or defective tooth
with access for structure (must be at
condensation and least as wide as the
outline form), narrowest condenser).
terminating on
smooth tooth
structure.
 Principles Rationale

4. If marginal ridge is If not included the

unsupported or very marginal ridge may fail
thin it should be (amalgam will be
included, resulting in stronger than the
a Class II unsupported enamel)
preparation.
 Principles Rationale

III. RESISTANCE/ RETENTION FORM

A. Depth = ½ mm into Minimum depth is

dentin (approx. 2 mm required to provide
measured at triangular sufficient bulk to
ridges). prevent fracture and
retain the amalgam.
 Principles Rationale

B. Pulpal floor

Uniform thickness of
1. Smooth and flat restorative material.

2. Parallel to the occlusal resists occlusal stress

plane (resistance form) and
forces of condensation.
 Principles Rationale

C. Buccal and lingual walls

1. Smooth and curved Facilitates adaptation

mesio-distally. of amalgam and
elimination of weak
tooth structure.
2. Smooth and straight
pulpo-occlusally.
 Principles Rationale

3. Converge slightly To provide mechanical

pulpo-occlusally in lock or retention to the
areas of triangular occlusal portion and crate
ridges (60). bulk at the margins.
 Principles Rationale

4.Diverge slightly protects buccal and lingual

pulpo-occlusally in surfaces from being
buccal and lingual undermined (RESISTANCE
groove extensions FORM).
(60).
 Principles Rationale

D. Mesial and distal wall

1. Smooth and straight facilitates adaptation

of amalgam and
elimination of weal
tooth structure.
 Principles Rationale

2. Diverges slightly protects marginal ridge

pulpo-occlusally form being undermined or
(forms an obtuse weakened (enamel must
angle with pulpal be supported be dentin)
floor).
 Principles Rationale

IV. CAVITY FINISH

A. Pulpo-occlusal line increases retention of the

angle is well defined amalgam restoration and
(no point angles are preparation is more easily
present) and follows visualized.
general
configuration of
cavosurface outline.
 Principles Rationale

B. Cavosurface margins

easier to visualize and

1. Sharp (well defined) carve.

2. Sound (well supported) provides marginal

integrity.
 Principles Rationale

C. Cleanliness – cavity facilitates adaptation of

is free of debris amalgam to the cavity and
and moisture. improves the physical
properties of the
restoration by elimination of
void or foreign material.
 Principles Rationale

V. TISSUE RESERVATION

preserves isolation,
A. Rubber dam is intact eliminates moisture.

B. Adjacent tooth structure conservation of tooth

and restorations are structure.
intact

prevention of post-
C. Adjacent soft tissue operative pain and
(perio-dontium) is intact inflammation.