This document outlines the 9 steps in cavity preparation for class I dental restorations:
1. Outlining the cavity and initial depth preparation.
2. Developing the primary resistance form to withstand forces.
3. Adding primary retention features like cavity convergence.
4. Adding convenience features for restoration placement.
5. Removing infected material and old restorations.
6. Applying pulp protection as needed.
7. Adding secondary resistance and retention features like bonding agents.
8. Finishing external walls for optimal margins.
9. Cleaning, inspecting, and sealing the preparation prior to restoration.
3. Steps In Cavity Preparation
For Class I Restorations
Guided by: Dr. Anubhav Sood
Presented by: H. Parikshit
14D0959
4. Cavity preparation
Definition (Acc to Sturdevant): Tooth preparation is
the mechanical alteration of a defective, injured, or
diseased tooth to receive a restorative material that re-
establishes a healthy state for the tooth, including
esthetic corrections where indicated and normal form
and function.
5. STAGES IN CAVITY PREPARATION
INITIAL STAGES
1. OUTLINE FOR AND INITIAL DEPTH
2. PRIMARY RESISTANCE FORM
3. PRIMARY RETENTION FORM
4. CONVENIENCE FORM
FINAL STAGES
5. REMOVAL OF ANY INFECTED DENTIN OR OLD
RESTORATIONS
6. PULP PROTECTION
7. SECONDARY RESISTANCE AND RETENTION FORM
8. PROCEDURES FOR FINISHING EXTERNAL WALLS
9. FINAL PROCEDURES- CLEANING, INSPECTING AND
SEALING
6. Step 1: Outline Form And Initial Depth
Definition (Acc to Sturdevant): : Placing the preparation margins in the positions
they will occupy in the final preparation, preparing an initial depth of 0.2-0.8mm
pulpally of the DEJ
Principles:
1. All the friable or weakened enamel usually
should be removed.
2. All faults should be included
3. All margins should be placed in a position to
afford good finishing of the margins of the
restorations
7. Features:
1. Preserving cuspal strength.
2. Prserving marginal ridge strength.
3. Minimizing faciolingual extensions.
4. Using enameloplasty.
5. Connecting two faults or tooth preparation.
6. Restricting the depth of the preparation
into dentin to be maximum of 0.2mm.
8. Step 2: Primary resistance form
Definition (Acc to Sturdevant): : Defined as the shape and placement of the preparation
walls that best enable the restoration and the tooth to withstand without fracture,
masticatory forces delivered principally in the long axis of the tooth.
Principles:
1. Box shape with a relatively flat floor
2. To restrict the extension of external walls
3. Slight rounding of internal line angles
4. To cap weak cusps and include enough of weakened tooth within the restoration
5. To provide enough thickness of restorative material
6. To bond the material to tooth structure when appropriate
9. Features:
1. Relatively flat floors.
2. Box shape.
3. Inclusion of weakened tooth structure.
4. Preservation of cusps and marginal ridges.
5. Rounded internal line angles.
6. Adequate thickness of restorative material.
10. Step 3: Primary retention form
Definition (Acc to Sturdevant): : It is the shape or form of the conventional preparation
that resists displacement of removal of the restoration by tipping or lifting forces .
Principles:
1. Material is retained in the tooth by developing external tooth walls that converge
occlusally.
2. Cavosurface angle = 90⁰.
Features :
1. Occlusal convergence
2. Elastic deformation of dentin
3. Dovetails
4. Parallel walls for inlays
5. Frictional retention of dentin
11. Step 4: convenience form
Definition (Acc to Sturdevant): : convenience form is the shape or form of the
preparation that provides for adequate observation, accessibility, and ease of
operation in preparing and restoring the tooth
Features:
1. Adequate extensions for filling and finishing
2. Contra angling of the hand instrument.
12. Step 5: Removal of any infected dentin or
old restorations.
Definition (Acc to Sturdevant): : It is the elimination of any infected carious tooth
structure or faulty restorative material left in the tooth after initial tooth
preparation.
Infected dentin: It is the irreversible demineralized and denatured layer with bacterial
invasion. Very soft, moist and easy to remove with a spoon excavator.
Affected dentin: Dentin is partially demineralized (leatherysofter than normal),
collagen is not denatured and contains minimal to no bacteria.
13. Step 6: Pulp Protection
When remaining dentin thickness is less, pulpal injury can occur because of:
1. Heat production,
2. high speed burs with less effective coolants,
3. Irritating restorative materials,
4. Galvanic currents,
5. Excessive masticatory forces transmitted through restorative material,
6. Ingress of microorganisms and their noxious products through microleakage.
Pulp protection is achieved using liners, varnishes and bases depending upon:
1. The amount of remaining dentin thickness
2. Type of restorative material used
14. Step 7: . Secondary resistance and retention form
The Secondary resistance and retention forms are of two types:
1. Mechanical preparation features
2. Treatments of the preparation walls with etching, priming and adhesive materials.
Mechanical features
1. Retention locks, grooves and coves
2. Groove extensions – for cast metal
3. Skirts – for cast gold
4. Beveled enamel margins – for cast gold, composite
5. Pins, slots, steps and amalgam pins
15. Step 8. Procedures for finishing external walls
Definition (Acc to Sturdevant): : It is the further development, when indicated, of a
specific cavosurface design and degree of smoothness and roughness that
produces the maximum effectiveness of the restorative material being used.
Objectives:
1. To create the best marginal seal.
2. Afford a smooth marginal junction.
3. Provide maximal strength of the tooth and the restorative material at and near the
margin.
16. Step 9: Cleaning, inspecting and sealing
• This includes the removal of debris, drying of the preparartion and final inspection
before placing restorative materials.
• Cleaning of the preparation can be done by using warm water.
• Drying can be done using air, dry cotton pellets. It is important that teeth are not
dehydrated by overuse of air or hot air.
17. FEATURES AMALGAM COMPOSITE
OUTLINE FORM • INCLUDE FAULT
• MAY EXTEND TO PROXIMAL
AREA
• INCLUDE ADJACENT
SUSPICIOUS AREA
• SAME
• SAME
• NO
PULPAL DEPTH UNIFORM, 1.5 mm REMOVE FAULT
AXIAL DEPTH UNIFORM 0.2-0.5mm INTO DEJ REMOVE FAULT
CAVOSURFACE MARGIN = 90⁰ >/= 90⁰
BEVELS NONE EXCEPT GINGIVAL MAY REQUIRE FOR LARGE
PREPARATIONS
TEXTURE OF PREPARED WALLS SMOOTH ROUGH
1⁰ RETENTION FORM OCCLUSAL CONVERGENCE BONDING
2⁰ RETENTION FORM GROOVES, SLOTS, LOCKS, PINS BONDING
RESISTANCE FORM FLAT FLOORS, ROUNDED ANGLES NO SPECIAL FORM
BASE MATERIAL Zn3(PO4)2
ZINC POLYCARBOXYLATE
RMGIC
SEALER GLUMA DESENSITIZER BINDING SYSTEM USED
Since our first year to final year……… We moved from micromotor to airotor, phantom head to patients head …. Morter pestle in PCO to amalgamator in clinics. So many things have changed. But there is one thing that been the same since then.
That’s nothing but … CAVITY PREPARATION
A very good morning to one and all. I parikshit harnoor, final yr BDS is here to present my seminar on STEPS IN CAVITY PREPARATION FOR CLASS 1 RESTORATIONS
