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2. 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.

3.  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.

4. 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.

5. 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.

6. 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.

7.  The mesial and distal wall
should have a slant or slight
divergence from the pulpal
floor outward to avoid
undermining the marginal
ridges.

8. 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.

9.  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.

10. Obtaining the
Resistance and
 The resistance form hereForms
Retention 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.

11. 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.

12. 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.

13. 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.

14. Operative
Procedures
Armamentarium
High speed handpiece
Burs #330, 56
Hoe
Hatchet R&L
Wedel staedt chisel

15. 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.

16.  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.

17.  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.

18.  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.

19. 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.

20. 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.

21. 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.

22. 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.

23. 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.

24. 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.

25. 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.

26. 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.

27. 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.

28. 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.

29. 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.

31. 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.

32. 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).

33. 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

34. 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).

35. 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).

36. 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.

37. 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.

38. 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.

39. 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.

40. 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.

41. 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.

42. 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.

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

44. Principles
Rationale
D. Mesial and distal wall
1. Smooth and straight facilitates adaptation
of amalgam and
elimination of weal
tooth structure.

45. 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).

46. 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.

47. Principles
Rationale
B. Cavosurface margins
easier to visualize and
1. Sharp (well defined) carve.
2. Sound (well supported) provides marginal
integrity.

48. 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.

49. 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.