This document discusses various classifications and principles of cavity preparation in dentistry. It describes Black's classification which categorizes cavities into classes I-V based on their location. It also discusses modifications to Black's classification by Charbeneau and Sturdevant. The document outlines principles of cavity preparation for different classes of cavities, including the goals of preserving tooth structure and maintaining proper cavity design and margins. It compares cavity preparation techniques for primary and permanent teeth. In summary, the document provides an overview of common cavity classification systems and guidelines for preparing cavities based on their location and extent in the tooth structure.

1. PRINCIPLES
AND
CONCEPTS OF CAVITY
PREPARATION
• Chinthamani Laser Dental College

2. Introduction

3. CLASSIFICATION

4. BLACK’S CLASSIFICATION
Class I lesion
Lesions that begin in the structural defects
of teeth such as pits, fissures and
defective grooves.
Locations include
• Occlusal surface of molars and premolars
• Occlusal two-thirds of buccal and lingual
surfaces of molars
• Lingual surface of anterior tooth

6. Class II Lesions
They are found on the proximal surfaces of
the bicuspids and molars.
• Areas for class II decay involve:
– Two-surface restoration of a posterior
tooth.
– Three-surface restoration of a posterior
tooth.
– Four- or more surface restoration of a
posterior tooth.

8. Class III lesions
Lesions found on the proximal
surfaces of anterior teeth
that do not involve or
neccesitate the removal of the
incisal angle.

10. Class IV lesions
Lesions found on the proximal
surfaces of anterior teeth
that involves the incisal angle.

11. Fig. 48-9 Class IV restoration.

12. Class V lesion
Lesions that are found on the gingival third of
the facial and lingual surfaces of the
anterior and posterior teeth.
Class VI
Lesions involving cuspal tips and incisal edges
of teeth.

13. OTHER MODIFICATIONS
CHARBENEU’S CLASSIFICATION
• Class II: Cavities on single proximal
surface of bicuspids and molars.
• Class VI: Cavities on both mesial and
distal proximal surfaces of posterior
teeth that will share a common occlusal
isthumus.
• Lingual surfaces of upper anterior teeth
• Any other usually located pit or fissure
involved with decay.

14. STURDEVANT ’S CLASSIFICATION
CAVITY
FEATURE
Simple cavity
A cavity involving only one tooth
surface
Compound cavity
A cavity involving two surfaces of
a tooth
Complex cavity
A cavity involves more than two
surfaces of a tooth.

15. FINN’S MODIFICATION OF BLACK’S
CAVITY PREPARATION FOR PRIMARY
TEETH
• Class I: cavities involving the pits and fissures
of the molar teeth and the buccal and lingual pits
of all teeth.
• Class II: cavities
involving proximal surface of
molar teeth with access established from the
occlusal surface.
• Class III: cavities involving proximal
surfaces
of anterior teeth which may or may not involve a
labial or a lingual extention.

16. Class IV:
• Cavities of the proximal surface of an
anterior tooth which involve the
restoration of an incisal angle.
Class V
• Cavities present on the cervical third of
all teeth of all teeth including proximal
surface where the marginal ridge is not
included in the cavity preparation.

17. BAUME’S CLASSIFICATION
• Pit and fissure cavities
• Smooth surface cavities

18. CLASSIFICATION BY MOUNT
AND HUME[1998]
• This new system defines the extent
and complexity of a cavity and at the
same time encourages a conservative
approach to the preservation of
natural tooth structure. This system
is designed to utilize the healing
capacity of enamel and dentin.

19. THE THREE SITES OF
CARIOUS LESIONS
• SITE I:
• Pits, fissures and enamel defects on
occlusal surfaces of posterior teeth or
other smooth surfaces.
• Proximal enamel immidiately below areas
in contact with adjacent teeth.
• The cervical one-third of the crown or
following gingival recession, the exposed
root

20. THE FOUR SIZES OF CARIOUS
LESION
• Size 1–minimal involvement in dentin just
beyond treatment by remineralisation alone
• Size 2-moderate involvement of dentin.
Following cavity preparation, remaining
enamel is sound well supported by dentin and
not likely to fail under normal occlusal load.
The remaining tooth structure is sufficiently
strong to support the restoration.
• Size 3-the cavity is enlarged beyond

21. moderate .the remaining tooth structure is
weakened to the extent that cusps or incisal
edges are split or are likely to fail or left
exposed to occlusal or incisal load. The cavity
needs to be further enlarged so that the
restoration can be designed to provide
support and protection to the remaining tooth
structure.
Size 4-extensive caries with bulk loss of tooth
structure has already occurred.

22. PRINCIPLES OF CAVITY
PREPARATION
Conventional concept [Black’s
concept]
• Incisors and canine
• Molars and premolars
• Gingival third cavities

23. Principles of Cavity Preparation

24. Principles of Cavity
Preparation− cont’d
Final cavity preparation

25. Patient Preparation for
Restorative Procedures
• Inform the patient of the procedure to
be performed and what to expect during
the treatment.
• Position the patient correctly for the
dentist and the type of procedure.
• Explain each step as the procedure
progresses.

26. RECENT CONCEPT

27. IATROGENIC FACTORS
AFFECTING DENTAL PULP

30. CLASS I CAVITY

31. • Incipient lesion
• #34 inverted cone bur is used to
penetrate the enamel and 0.5mm or less
into the dentin
• Grooves and fissures is completed
• Smoothen the walls and finish the cavity
• Occlusal enamel walls will be
approximately parallel to the axis of the
tooth
• Pulpal wall flat and smooth.

32. Extensive area
#2 or #4 round bur can be used to enter
and remove the decay
Bur should run at a slower speed
Light feather touch to sweep out deepest
penetrations of decay.
Smoothen the enamel walls and finishing
is done

33. • Final occlusal outline form will consist of
sweeping curves and be devoid of sharp
angles.
• Bevel on the enamel should not be
placed at the cavosurface angle because
of poor edge strength of amalgam.

35. CLASS II CAVITIES

36. PROXIMAL BOX• The farther the gingival wall is carried
down, the deeper pulpally must be the
axial wall to maintain the proper 1mm
width .
GINGIVAL WALL• Width should be approximately 1mm
AXIAL WALL• Smaller restoration flat
• Larger restoration-curve to parallel the
outside contour

40. • CONVERGENCE-the proximal box line angles and
walls should converge toward the occlusal
approximately following the buccal and lingual
surfaces of the tooth.
• 90 degree cavosurface angle shold be maintained.
• LINE ANGLES-the buccogingival and linguogingival
line angles can be very slightly rounded.
• CAVOSURFACE-the buccal and lingual walls should
be at right angles to the surface of the tooth and in
the direction of enamel rods.

41. • CERVICAL ENAMEL RODS- at the cervical
margin the rods incline slightly toward the
occlusal.
• RETENTION-retention grooves may be
placed into the buccoaxial and lingual-axial
line angles ,but in a fashion which will not
undermine the enamel walls.
• ISTHUMUS WIDTH-on the occlusal
surface the isthumus width should rarely
exceed the width of a channel cut.
• AXIOPULPAL LINE ANGLE-this can be
rounded with a bur or hand instrument by
sharp enamel hatchets.

42. PULPAL WALLthe pulpal wall may be flat or rounded slightly and
should be preparedso it is about 0.5mminto the
dentin
OCCLUSAL WALLthe buccal and lingual walls of the occlusal step may
converge slightly as they approach the occlusal
surface.
OCCLUSAL DOVETAILthis should be extended to include the susceptible
or carious areas of each specific tooth. The
outline form should be rounded,smooth,and
graceful with a definite lock on the occlusal.

43. SPECIFIC MODIFICATIONS
• DEEP PROXIMAL CARIES
• SMALL FIRST MOLARS
• THIN CUSPS

44. DIFFERENCES IN CAVITY
PREPARATION FOR
PRIMARY AND PERMANENT
TEETH

45. PRIMARY TEETH
PERMANENT TEETH
DEPTH OF THE CAVITY
0.5mm into dentin
0.2mm into dentin
OCCLUSAL TABLE
Occlusal table is narrow as Occlusal table is wider
the buccolingual width of
than the primary teeth
the tooth is less
CONTACT POINT
/POINT
Because of the presence
of contact area, buccal
and lingual margins of the
interproximal box must
extend far enough
towards the embrasure at
the gingival margin to
make them accessible for
cleaning.
Because of the presence
of contact area, buccal
and lingual margins of the
interproximal box don’t
have to extend too far
into the embrasure.

46. MARKED CERVICAL
CONSTRICTION
Because of the marked
cervical constriction the
floor of the cavity can
become too narrow if
placed more gingivally
ISTHUMUS OF THE
CAVITY
Isthumus is narrow
because the buccolingual
width of the tooth is
less.cavities with wide
isthumus can lead to
fracture of the tooth.
BEVEL IN CAVOSURFACE Bevel is not given in the
MARGIN OF GINGIVAL
cavosurface margin of
SEAT
gingival seat
OCCLUSAL ASPECT OF
THE PROXIMAL BOX
Must be kept narrow to
prevent weakening of the
cusp
The cervical constriction
is not that marked
therefore sufficient
width of the floor of
interproximal box can be
maintained.
Isthumus is wider
compared to primary
teeth.
Bevel is given in the
gingival seat
Its not that narrow

47. GINGIVAL SEAT
PLACEMENT
They are placed clear of
contact with the
adjacent tooth, so that
the margins of the
restorations can be
cleaned.
It is not that wide.
BUCCAL AND LINGUAL
WALLS OF THE
PROXIMAL BOX
Because of the wider
contact area the buccal
and the lingual walls of the
interproximal diverge
buccally and lingually to
clear the contact area.
Because of the prasence
of contact point the
buccal and the lingual walls
of the interproximal need
not be diverged towards
the embrasure.
MOD CAVITY
Should not be restored
for amalgam alone.
It may be restored with
amalgam.

48. THANK YOU
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