The document outlines the principles and steps involved in cavity preparation for dental restorations, emphasizing the definition, classification, and techniques of tooth preparation. It details the various classes of tooth preparations, fundamental principles of design, and the stages from initial preparation to finishing procedures. Additionally, it discusses the importance of conserving tooth structure and ensuring effective bonding for different types of restorative materials.

1. PRINCIPLESOF CAVITY
PREPARATION
SUBMITTED BY:
NAME- CHHAYA DEV
ROLL NO- 106
BDS 4TH YEAR

2. DEFINITION:
TOOTH PREPARATION IS DEFINED AS THE MECHANICAL ALTERATION OF A DEFECTIVE, INJURED OR
DISEASED TOOTH SUCH THAT PLACEMENT OF RESTORATIVE MATERIAL REESTABLISH NORMAL
FORM (AND THEREFORE FUNCTION) INCLUDING ESTHETIC CORRECTION, WHERE INDICATED.
IN THE PAST, MOST RESTORATIVE TREATMENT WAS FOR CAVITATED CARIOUS LESION AND THE TERM
CAVITY WAS USED TO DESCRIBE A CARIOUS LESION THAT HAD PROGRESSED TO THE POINT THAT
THERE WAS A BREACH IN THE SURFACE INTEGRITY OF THE TOOTH. LIKEWISE, WHEN THE AFFECTED
TOOTH WAS TREATED, THE CUTTING OR PREPARATION OF THE REMAINING TOOTH STRUCTURE (TO
RECEIVE A RESTORATIVE MATERIAL) WAS REFERRED TO AS CAVITY PREPARATION. CURRENTLY,
MANY INDICATION FOR TREATMENT ARE NOT RELATED TO CARIOUS DESTRUCTION AND THE
PREPARATION OF THE TOOTH NO LONGER IS REFERRED TO AS CAVITY PREPARATION BUT AS TOOTH
PREPARATION

3. FACTORS TO CONSIDER BEFORE AND DURING TOOTH
PREPARATION:

4. CLASSIFICATION OF TOOTH PREPARATION:
GV BLACK PRESENTED A CLASSIFICATION OF TOOTH PREPARATION ACCORDING TO DISEASED AND
ANATOMIC AREAS INVOLVED AND BY THE ASSOCIATED TYPE OF TREATMENT:
CLASS I PREPARATIONS - ALL PREPARATIONS REQUIRED TO TREAT PIT AND FISSURE CARIES. THESE
INCLUDE PREPARATION ON:
1. OCCLUSAL SURFACE OF PREMOLAR AND MOLAR
2. OCCLUSAL TWO THIRD OF THE FACIAL AND LINGUAL SURFACE OF MOLARS
3. THE LINGUAL SURFACE IS OF MAXILLARY INCISORS
CLASS II PREPARATIONS - PREPARATIONS REQUIRED TO CORRECT CARIES LESION THAT DEVELOP IN
THE PROXIMAL SURFACES OF POSTERIOR TEETH.
CLASS III PREPARATIONS - PREPARATIONS REQUIRED TO CORRECT CARIES LESION THAT DEVELOPED
IN THE PROXIMAL SURFACES OF ANTERIOR TEETH THAT DO NOT INCLUDE THE INCISAL EDGE.

6. CLASS IV PREPARATIONS - PREPARATIONS REQUIRED TO CORRECT CARIOUS LESION OR OTHER
DEFECTS THAT DEVELOP IN THE PROXIMAL SURFACES OF ANTERIOR TEETH THAT INCLUDE THE
INCISAL EDGE.
CLASS V PREPARATIONS - PREPARATIONS REQUIRED TO CORRECT CARIES LESION OR OTHER
DEFECTS THAT DEVELOPED IN THE GINGIVAL THIRD OF THE FACIAL OR LINGUAL SURFACE OF ALL
THE TEETH.
CLASS VI PREPARATIONS - PREPARATIONS REQUIRED TO CORRECT CARIOUS LESION OR OTHER
DEFECTS THAT DEVELOP IN THE INCISAL EDGE OF ANTERIOR TEETH OR THE OCCLUSAL CUSP TIP OF
POSTERIOR TEETH.

7. TOOTH PREPARATION WALLS:
THE PROCESS OF CREATING A PREPARATION IN A TOOTH RESULTS IN THE FORMATION OF PREPARATION WALLS OR
FLOORS:
• AN INTERNAL WALL IS A PREPARED SURFACE THAT DOES NOT EXTEND TO THE EXTERNAL TO THE SURFACE. THERE
ARE TWO TYPES OF INTERNAL WALLS;
1. THE AXIAL WALL IS AN INTERNAL WAS THAT IS ORIENTED PARALLEL TO THE LONG AXIS OF THE TOOTH
2. THE PULPALWALL IS AN INTERNAL WALL THAT IS ORIENTED PERPENDICULAR TO THE LONG AXIS OF THE TOOTH
AND IS LOCATED A OCCLUSAL TO THE PULP. THIS INTERNAL WALL MAY ALSO BE REFERRED TO AS PULPUL FLOOR
• AN EXTERNAL WALL IS PREPARED SURFACE THAT EXTENDS TO THE EXTERNAL TOOTH SURFACE. THE EXTERNAL
WALL THAT IS APPROXIMATELY HORIZONTAL MAY ALSO BE REFERRED TO AS PREPARATION FLOOR.
1. THE ENAMEL WALL IS THAT PORTION OF PREPARED EXTERNAL WALL CONSISTING OF ENAMEL..
2. THE DENTINAL WALL IS THAT PORTION OF REPAIRED EXTERNAL WALL CONSISTING OF DENTIN.

9. BASIC PRINCIPLES OF CAVITY PREPARATION GIVEN BY G V BLACK:

10. STEPS OF TOOTH PREPARATION:
INITIAL TOOTH PREPARATION STAGE:
STEP 1 - INITIAL DEPTH AND OUTLINE FORM
STEP 2 - PRIMARY RESISTANCE FORM
STEP 3 - PRIMARY RETENTION FORM
STEP 4 - CONVENIENCE FORM
FINAL TOOTH PREPARATION STAGE:
STEP 5 - REMOVAL OF DEFECTIVE RESTORATION MATERIAL AND/OR SOFT DENTIN
STEP 6 - PROTECTION PROTECTION
STEP 7 - SECONDARY RESISTANCE AND RETENTION FORM
STEP 8 - EXTERNAL WALL FINISHING
STEP 9 - FINISHING PROCEDURES DEBRIDEMENT AND INSPECTION

11. STEP 1 - INITIAL DEPTH AND OUTLINE FORM
THE FIRST STEP IN THE TOOTH PREPARATION IS TO ESTABLISH THE INITIAL DEPTH AND THEN AT THE DEPTH,
EXTEND THE WALLS OF THE PREPARATION UNTIL THE JUNCTION BETWEEN THE ENAMEL AND SUPPORTING THE
DENTIN IS UNCOMPROMISED.
THE PERIPHERAL WALLS DETERMINE THE OVERALL OUTLINE OF THE PREPARATION WHICH IS REFERRED TO AS
OUTLINE FORM.
THE INITIAL DEPTH OF THE PREPARATION IS 0.2 MM INTERNAL TO THE DEJ OR 0.8 MM INTERNAL TO THE NORMAL
ROOT-SURFACE
AN EXCEPTION TO THIS INITIAL DEPTH OF 0.2 MM INTERNAL TO THE DEJ IS WHEN THE ENAMEL IS THIN AND
GREATER DEPTH IS NECESSARY FOR THE STRENGTH OF THE RESTORATIVE MATERIAL THAT WIRESTORATIV. THE
INITIAL PREPARATION DEPTH IS 0.5 MM INTERNAL TO THE DEJ IN ANY AREA WHERE SECONDARY RETENTION
FEATURE ARE BEING PLANNED.

13. PRINCIPLES:
THE OUTLINE FORM IS DESIGNED REGARDLESS OF THE TYPE OF TOOTH PREPARATION
SUCH THAT:
1. ALL UNSUPPORTED OR WEAKEND ENAMEL USUALLY REMOVED
2. ALL FAULTS ARE INCLUDED
3. ALL PREPARATION MARGINS ARE USUALLY PLACED IN A POSITION THAT
ALLOWS INSPECTION AND FINISHING OF THE SUBSEQUENT REGISTRATION
MARGINS

14. FEATURES:
GENERALLY THE TYPICAL FEATURES OF ESTABLISHING PROPER OUTLINE FORM AND INITIAL DEATH
ARE:
1. PRESERVING CUSPAL STRENGTH
2. PRESERVING MARGINAL RIDGE STRENGTH
3. MINIMISING FACIOLINGUAL EXTENSIONS
4. CONNECTING TO CLOSE DEFECTS OR TOOTH PREPARATIONS
5. RESTRICTING THE DEPTH OF THE PREPARATION INTO DENTIN

15. STEP 2 - PRIMARY RESISTANCE FORM
PRIMARY RESISTANCE FORM MAY BE DEFINED AS THE SHAPE AND PLACEMENT OF THE PREPARATION
WAPLS THAT ENABLE THE REMAINING TOOTH STRUCTURE AS WELL AS THE ANTICIPATED
RESTORATION TO WHITHSTAND MASTICATORY FORCES PRIMARILY ORIENTED PARALLEL TO THE
LONG AXIS OF THE TOOTH.

16. PRINCIPLES:
THE FUNDAMENTAL PRINCIPLES INVOLVED IN OBTAINING PRIMARY ASSISTANCE FROM INCLUDE:
• FIRST PRINCIPLE OF MINIMAL EXTENSION - PRIMARY RESISTANCE FORM IS OBTAINED THROUGH USE OF
A PREPARATION DESIGN THAT CONSERVE AS MUCH HEALTHY TOOTH STRUCTURE AS POSSIBLE
• SECOND PRINCIPLE OF HORIZONTAL FLOORS – THE RELATIVELY HORIZONTAL PUPPAL AND GINGIVAL
WALLS PREPARED PERPENDICULAR TO THE TOOTTH’S LONG AXIS, HELPS THE ROTATION RESIST THE
OCCLUSAL FORCES AND LIMIT THE LIKELIHOOD OF THE TOOTH FRACTURE FROM WEDGING EFFECT
CAUSED BY OPPOSING CUSPS
• THIRD PRINCIPLE OF ROUNDED LINE ANGLE - TRANSITIONS BETWEEN THE WALLS OF THE PREPARATION
(I.E. THE INTERNAL LINE ANGLE ) ARE SLIGHTLY ROUNDED SO AS TO LIMIT STRESS CONCENTRATION IN
THESE AREAS WHICH INCREASED TOOTH RESISTANCE TO FRACTURE

17. • FOURTH PRINCIPLE OF RESTORATIVE MATERIAL THICKNESS - PREPARATION DESIGN MUST ALLOW
FOR ADEQUATE THICKNESS OF POLYCRYSTALLINE RESTRICTIVE MATERIALS TO ENSURE
ADEQUATE PRIMARY RESISTANCE TO RESTORATION FRACTURE
• FIFTH PRINCIPLE OF CAPPING (WHEN REQUIRED) - IT MAY BE NECESSARY TO REDUCE CUSPS THAT
NO LONGER HAVE SUFFICIENT DENTIN SUPPORT AND COVER THEM WITH AN ADEQUATE
THICKHNESS OF RESTORATIVE MATERIAL IN ORDER TO PROVIDE RESISTANCE TO FRACTURE OF THE
TOOTH AND/OR THE RESTORATIVE MATERIAL.

18. STEP 3 - PRIMARY RETENTION FORM
PRIMARY RETENTION FORM IS THE SHAPE OR FORM OF THE PREPARATION THAT PREVENTS
DISPLACEMENT OR REMOVAL OF THE RESTORATION BY KEEPING A LIFTING FORCES IN MANY
RESPECTS THE RETENTION FORM AND RESISTANCE FORMER ACCOMPLISHED AT THE SAME
TIME.

19. • PRIMARY RETENTION FORM FOR AMALGAM RESTORATION:
AMALGAM RESTORATION OF CLASS I OR II PREPARATION IS RETAINED BY DEVELOPING EXTERNAL TOOTH WALLS THAT CONVERSE
OCCLUSALLY. IN THIS WAY, WHEN AMALGAM IS PLACED IN PREPARATION AND HARDENS, IT CANNOT BE DISLODGED
• PRIMARY RETENTION FORM FOR COMPOSITE RESTORATION:
COMPOSITE RESTORATION ARE PRIMARILY RETAINED IN THE TOOTH BY MICROMECHANICAL AND CHEMICAL BONDING THAT IS
ESTABLISHED BETWEEN THE RESTORATION AND TOOTH STRUCTURE. IN SUCH RESTORATIONS, THE PREPARATION SURFACE OF
ENAMEL AND DENTIN ETCHED BY CREATION OF ACIDIC CONDITIONS AND THEN INFILTRATED WITH RESIN BASED ADHESIVE
MATERIAL BEFORE PLACEMENT OF COMPOSITE

20. • PRIMARY RETENTION FORM FOR CAST METAL RESTORATION:
1. CAST METAL INTRACORONAL RESTORATION, REFERRED TO AS INLAY RESTORATION RELY ON
DIVERGING VERTICAL WALLS THAT ARE ALMOST PARALLEL
2. IN CLASS II PREPARATIONS INVOLVING ONLY ONE OF THE TWO PROXIMAL SURFACES, AN
OCCLUSAL DOVETAIL MAY AID IN PREVENTING THE TIPPING OF THE RESTORATION BY GLOZELL
FORCES
3. THE OTHER PRIMARY RETENTION FORM FOR CAST METAL RESTORATIONS IS THE USE OF A LUTING
AGENTS THAT BONDS THE RESTORATION TO THIS TOOTH STRUCTURE

21. STEP 4 - CONVENIENCE FORM
CONVENIENCE FORM IS THE SHAPE OR FORM THAT PROVIDE ADEQUATE OBSERVATION, ACCESSIBILITY AND
EASE IN THE PREPARATION AND RESTORATION OF THE TOOTH.
EXTENSION OF DISTAL, MESIAL, FACIAL OR LINGUAL WALLS SO AS TO GAIN ADEQUATE ACCESS TO DEEPER
AREAS OF THE PREPARATION.
EXTENSION OF THE PROXIMAL WAS SO AS TO OBTAIN CLEARANCE WITH AN ADJACENT PROXIMAL SURFACE.
THE ARBITRARY EXTENSION OF FACIAL MARGINS ON ANTERIOR TEETH IS USUALLY CONTRAINDICATED FOR
AESTHETIC REASONS.
CONVENIENCE FORM OF VARIOUS PROCEDURE ARE ALWAYS ACCOMPLISHED IN LIGHT OF THE GOAL OF
CONSERVING AS MUCH HEALTHY TOOTH STRUCTURE AS POSSIBLE

22. STEP 5 – REMOVAL OF DEFECTIVE RESTORATIVE MATERIAL
AND/OR SOFT DENTIN
ONCE THE CARIES LESION HAS BEEN FULLY EXPOSED (VIA INITIAL PREPARATION), CAREFUL PULPAL AND/OR
AXIAL EXTENSION IS ACCOMPLISHED SO AS TO REMOVE DEFECTIVE RESTORATIVE MATERIAL AND/OR SOFT
DENTIN ( KNOWN AS INFECTED DENTIN CONTAINING MICROORGANISMS.
OLD RESTORATIVE MATERIAL MAY REMAIN ON THE PULPAL OR AXIAL WALLS AFTER INITIAL TOOTH
PREPARATION. THIS SHOULD BE REMOVED IF ANY OF THE FOLLOWING CONDITIONS ARE PRESENT:
1. OLD MATERIAL MAY NEGATIVELY AFFECT THE ESTHETIC
2. RADIOGRAPHIC EVIDENCE INDICATES CARIES LESION DEVELOPMENT UNDER THE OLD MATERIAL
3. TOOTH PULP WAS SYMPTOMATIC PREOPERATIVELY
4. DENTIN ALONG THE PERIPHERY OF THE REMAINING OLD RESTORATIVE MATERIAL IS SOFT
5. RETENTION OF EXISTING MATERIAL IS COMPROMISED AND MATERIAL IS EASILY DISLODGED

23. STEP 6 – PULP PROTECTION
DEEP DENTIN IS VERY POROUS AND SUSCEPTIBLE TO DESICCATION. DEEP DENTING ALSO IS
VERY POOR SUBSTRATE FOR SUBSEQUENT BONDING PROCEDURES.
THE THIN REMAINING WALL OF DENTIN PROVIDES LITTLE PROTECTION FROM:
1. HEAT GENERATED BY ROTARY INSTRUMENTS
2. NOXIOUS INGREDIENTS OF VARIOUS RESTORATOR MATERIAL
3. THERMAL CHANGES CONDUCTED THROUGH RESTORATIVE MATERIAL
4. FORCES TRANSMITTED THROUGH MATERIAL TO THE DENTIN
5. GALVANIC SHOCK
6. BACTERIA AND/OR BACTERIAL TOXINS THROUGH MY MICROLEAKAGE

24. LINERS:
LINERS ARE RELATIVELY THIN FILM MATERIALS THAT ARE USED TO COVER DEEP DENTIN IN ORDER
TO LIMIT DENTINAL TUBULAR FLUID FLOW, AND TO CREATE A PROTECTIVE THERMAL/PHYSICAL
BARRIER.
VARIOUS MATERIALS:
1. CALCIUM HYDROXIDE
2. RESIN-MODIFIED GLASS IONOMER (RMGI)
3. SUSPENSION OR DISPERSION OF ZINC OXIDE EUGENOL
4. MINERAL TRIOXIDE AGGREGATE (MTA) LINERS
BASES:
THE TERM BASE IS USED TO DESCRIBE THE PLACEMENT OF MATERIALS, USED IN THINKER
DIMENSIONS, BENEATH PERMANENT RESTORATIONS TO PROVIDE FOR MECHANICAL, CHEMICAL
AND THERMAL PROTECTION OF THE PULP.

25. SCHEMATIC VIEW OF NEED OF PULPAL
PROTECTION BELOW METALLIC RESTORATION

26. STEP 7 – SECONDARY RETENTION AND RESISTANCE FORM
MOST COMPUND AND COMPLEX CAVITY PREPARATION REQUIRE ADDITIONAL RETENTION
AND RESISTANCE FORM.
THE SECONDARY RETENTION AND RESISTANCE FORM ARE OF TWO TYPES:
1. MECHANICAL PREPARATION FEATURES:
• RETENTION GROOVES AND COVES
• PREPARATION EXTENSION
• BEVELLED ENAMEL MARGINS
• STEPS, AMALGAM PINS, SLOTS AND PINS
2. CAVITY WALL CONDITIONING:
PLACEMENT OF ETCHANT, PRIMER OR ADHESIVE ON PREPAREDWALL

27. STEP 8 – EXTERNAL WALL FINISHING
IT IS THE FURTHER DEVELOPMENT OF A SPECIFIC CAVOSURFACE DESIGN AND
DEGREE OF SMOOTHNESS THAT PRODUCES THE MAXIMUM EFFECTIVENESS OF THE
RESTORATIVE MATERIAL BEING USED.
OBJECTIVES:
• TO CREATE THE BEST MARGINAL SEAL POSSIBLE BETWEEN THE RESTORATIVE
MATERIAL AND TOOTH STRUCTURE
• TO AFFORD A SMOOTH MARGINAL JUNCTION
• TO PROVIDE MAXIMUM STRENGTH OF BOTH THE TOOTH AND RESTORATIVE
MATERIAL NEAR THE MARGINS

28. OCCLUSAL CAVOSURFACE
MARGIN
PROXIMAL CAVOSURFACE MARGIN

29. STEP 9 - FINAL PROCEDURES: DEBRIDEMENT AND INSPECTION
DEBRIDEMENT (CLEANING) OF THE TOOTH PREPARATION INVOLVES USE OF
THE AIR WATER SYRINGE TO REMOVE VISIBLE DEBRIS IN WATER AND THEN
EXCESS MOISTURE WITH A FEW LIGHT BURST OF AIR.

30. THANK YOU