This is the powerpoint presentation for Principles of Cavity preparation in the undergraduate level. It includes all the basic details a budding dentist has to know in the department of conservative dentistry. Hope you would learn better and enjoy learning.

1. -Presented by,
S R Neha
BDS 3rd Year

2. The principles of modern cavity preparation
was first described in 1986 by Dr. G V Black,
a man considered by many to be the “Father
of modern Restorative Dentistry” when his
original sequence of cavity was one of the
most important considerations of cavity
design.

3. Defined as the mechanical alteration of a
defective, injured or diseased tooth such that
placement of restorative material re-establishes
normal form and function including esthetic
corrections, where indicated.

4.  Conserve as much as healthy tooth structure as
possible.
 Remove all defects while simultaneously
providing proper protection of pulp.
 Allow for the esthetic placement of a
restorative material where indicated.

5. Teeth require intervention for various reasons:
 Caries lesion progression.
 Tooth fracture compromising form and
function.
 Congenital malformation.
 Previous restoration with inadequate occlusal
or proximal contact.

6. [Acc. to its location on tooth surface]
 CLASS 1 include all pit & fissure caries, caries
involving occlusal surface of molars and
premolars, occlusal 2/3rd of buccal & lingual
surface of molars, lingual surface of anterior
teeth and any other developmental defects.
 CLASS 2 caries involving proximal surface of
posterior teeth.
 CLASS 3 caries involving proximal surface of
anterior teeth that do not involve incisal edge.

7.  CLASS 4 caries involving proximal surface of
anterior teeth that also involves incisal edge.
 CLASS 5 caries involving gingival third of
facial or lingual surface of all teeth.
 CLASS 6 caries involving incisal edges of all
anterior teeth and cusp tips of all posterior
teeth.

10.  SIMPLE: Caries involving only one tooth
surface. Eg: Buccal pit.
 Compound: Caries involving two tooth
surfaces. Eg: Mesio-occlusal cavity.
 Complex: Caries involving three or more tooth
surfaces. Eg: Mesio-occluso-distal cavity

11.  Axial wall : An internal wall which is parallel
to long axis of tooth.
 Pulpal wall : An internal wall which is
perpendicular to long axis of tooth.
 Isthmus : It is the narrow space formed
between occlusal surface and proximal box of
Class II cavity preparartion.
 Cavosurface : It is the area formed by the
junction of prepared cavity wall and external
tooth surface.

12. 2 Stages
Initial Stage Final Stage

13. INITIAL STAGE:
Step 1: Initial depth and outline form.
Step 2: Primary resistance form.
Step 3: Primary retention form.
Step 4: Convenience form.
FINAL STAGE:
Step 5: Removal of defective restorative material
and/or soft dentin.
Step 6: Pulp protection.
Step 7: Secondary resiatnce and retention forms
Step 8: Finishing of external walls.
Step 9: Final procedures: Debridement & Inspection

14. INITIAL STAGES:
Outline Form
•Defined as “ the locations that the peripheries of
completed tooth preparation will occupy tooth
surface.”
•It is the shape or form of cavity where final cavity
preparation rests.

15. The typical features of establishing proper
outline form and initial depth are:
-The initial depth of preparation is 0.2mm
internal to DEJ or 0.8mm internal to normal root
surface such that it restricts the depth of
preparation into dentin.
-Preserving cuspal strength.
-Preserving marginal ridge strength.
-Minimizing faciolingual extensions.
-Connecting two close (<0.5mm apart) defects or
tooth preparations.

16.  Extent of caries lesion.
 Esthetic considerations.
 Restorative material to be used.
 Desired cavosurface marginal configuration.
 Include all defective pit and fissure caries that
cannot be corrected by enameloplasty.
 Convenience form.
 Correcting or improving occlusal relationships.

17. Primary Resistance Form
Defined as the shape and placement of the cavity
walls that best enables restoration of tooth to
withsthand , without fracture, the masticatory
forces delivered principally along the long axis of
tooth.

18. Methods Employed:
•Adequate depth of 0.5 mm in dentin provides the
required bulk for amalgam.
•Adequate width of the cavity at the isthmus,1/4th
of the intercuspal distance.
•Box shaped cavity with relatively flat pulpal floor.
•Including the weakened tooth structure.
•Rounded internal line angles and axio-pulpal line
angles rounded.
•Axial wall is convex and parallel to the outer
contour of tooth.

19.  Gingival cavosurface bevel below 20o.
 Reduction of cusp or cusp capping when
indiacted.
 Taper of mesial and distal walls, buccal and
lingual groove extensions.
 Cavosurface should form 90o butt joint (Flare) or
reverse ‘S’ curve.

20. Primary Retention Form
Defined as that shape or form of prepared tooth
margin that resists displacement or removal of
restoration from tipping or lifting forces.
-Irregular outline form
with dovetail.
-Occlusal interlocking.
-Inverse taper at buccal
and lingual walls.

21. Convenience Form
Defined as that shape or form of cavity that
provides for adequate observation, accessibility
and ease of operation in preparation and
restoration of the tooth.

22. -Extension of mesial, distal, facial or lingual walls to
gain adequate access to deeper portions of
preparations.
-Clearing or breaking contact of adjacent tooth.
-Placing gingival seat below contact.
-Use of instruments with smaller size, design for
better access.

23. FINAL STAGES:
Removal of defective restorative material
Old restorative material that remain on pulp or
axial walls after initial stages should be removed if
any of the foll. condns. are present.
Old amalgam material might be left under a new
composite restoration.

24.  Radiographic evidence in dictaes caries lesion
development under old material.
 The dention along the periphery of the
remaining old restorative material is soft.
 Retention of the existing material is
compromised and the material is easily
dislodged.

25. Pulp Protection
By avoiding,
Cutting across recessional lines.
Overcutting of dentin & unnecessary deepening
of floor of prepared cavity.
Unnecessary or excessive cutting of enamel.
Injudicious use of hand & rotary instruments at
bottom of deep cavities above roof of pulp.

26.  Avoiding heat generation during cavity
preparation.
 Use of caustics or chemical irritants like phenol
drugs or alcohol should be avoided.
 To avoid pulp injury, avoid trauma, speed ranges,
high pressure vibration.

27. Secondary Resistance and Retention Forms
2 Types
Mechanical
Features
Treatment of
prepn. walls with
etching, priming

28.  Retentive grooves and coves.
 Skirts.
 Bevelled enamel margins.
 Steps.
 Amalgam pins.
 Slots

31. Proper finishing of the external walls allows the
creation of an optimal marginal junction
between the restorative material and the tooth
structure.Thus there is a smooth transition
across the marginal junction and both tooth and
restorative material have maximal strength.

32. -To create a best possible marginal seal between
restorative material and tooth surface.
-To obtain smooth margin and function.
-To provide maximum strength for tooth and
restorative material.

33. -Walls must be supported by sound dentin i.e., no
unsupported enamel.
-Walls should have smooth surface & should
follow enamel rod direction.
-Cavosurface margin must be butt joint except at the
gingival cavosurface of Class II cavity.

34. Debridement and Inspection
Debridement of cavity preparation involves use of
the air/water syringe to remove visible debris
with water and then excess moisture with a few
light bursts of air.