This document provides information on tooth preparation fundamentals and techniques. It discusses the initial stages of tooth preparation including outline form and initial depth, primary resistance form, and primary retention form. The final stages are also outlined, including removal of infected material, pulp protection, and secondary resistance and retention forms. Modifications for amalgam preparations are described, such as box-only and tunnel preparations. The overall document serves as a guide for proper cavity preparation procedures and techniques.

1. Dr. Manjiri Honap
Department of Conservative Dentistry
and Endodontics
FUNDAMENTALS OF TOOTH
PREPARATION

2. FLOWCHART
• Recap of initial stage of tooth
preparation
• Final stage of tooth
preparation
• Modifications of cavity
preparation for amalgam

3. INITIAL TOOTH PREPARATION STAGE
• STEP 1: Outline Form and Initial depth
• STEP 2: Primary Resistance Form
• STEP 3: Primary Retention Form
• STEP 4: Convenience Form

4. OUTLINE FORM AND INITIAL DEPTH
• To determine and develop the outline form/ design while establishing the initial
depth.
• Extend the preparation to maintain sound tooth structure.
• Initial depth should be 0.2 -0.8 mm from dentinoenamel junction.
• Cuspal strength and marginal ridge strength should be preserved.
• Distance between two defects in tooth preparation is less than 0.5mm then
both the preparation of the tooth should be connected.
• Enemeloplasty : It involves removal of shallow enamel developmental fissure
or pit to create smooth ,saucer shaped surface that is self cleansing or easily
cleaned.

5. PRIMARY RESISTANCE FORM
• It is that form/shape of tooth preparation that enables the restoration to
withstand the masticatory forces without fracture.
• The pulpal floors should be relatively flat.
• Box like shape preparation
• Rounded internal line angles so that no dislodgement or fracture of
restoration.
• Adequate thickness of restorative material.
• Preserving the cuspal and marginal strength
• Consideration for cusp capping

6. PRIMARY RETENTION FORM
• tooth walls that converge occlusally
• The cavosurface angle - 90 degrees
• Dove tail preparation

8. CONVENIENCE FORM
• Shape or form of the preparation that provides for adequate observation,
accessibility, and ease of operation in preparing and restoring the tooth.

9. STAGES OF TOOTH PREPARATION
• FINAL STAGE OF TOOTH PREPARATION :
Step 5: Removal of any remaining infected dentin and/or old restorative
material, if indicated
Step 6: Pulp protection, if indicated
Step 7: Secondary resistance and retention forms
Step 8: Procedures for finishing external walls
Step 9: Final procedures: cleaning, inspecting, sealing

10. STEP 5: REMOVAL OF ANY REMAINING
INFECTED DENTIN
• Elimination of any infected carious tooth structure or faulty restorative
material left in tooth after initial preparation
• Spoon excavators/carbide burs

11. STEP 6: PULP PROTECTION
Pulp irritation etiology
• Heat generated by rotary instruments
• Some ingredients in various materials
• Thermal changes conducted through restorative materials
• Forces transmitted through materials, to dentin
• Galvanic shock

12. SECONDARY RESISTANCE AND RETENTION
FORM
Mechanical features
• Retention grooves,
• Pin retained amalgam
• Internal boxes, Skirts

15. AMALGA PINS
• Vertical posts of amalgam anchored in dentin
• Increase resistance and retention form

16. STEP 8: PROCEDURES FOR FINISHING THE
EXTERNAL WALLS
• Further development of degree of surface smoothness or roughness
that produces them max effects of a restorative material
FEATURES:
Design of the cavosurface angle
• 90° cavosurface angle for amalgam.

17. STEP 9: CLEANING , INSPECTING,
DESENSITIZING
• To free the prep of visible debris with water from the Syringe & then to
remove the visible moisture with a light burst of air from the Syringe
• Desensitizers:
• ◦ 5% Glutaraldehyde
• ◦ 35% 2-hydroxymethylmethacrylate

18. MODIFICATIONS OF AMALGAM PREPARATION
• Pre-requisites:
• ◦ 90º junction b/n amalgam & tooth
• ◦ Mech. Retention form [occlusally convergent prepartion]
• ◦ Adequate thickness of Amalgam

19. BOX ONLY
◦ For posterior tooth where proximal
surface require restoration but occlusal
surface is normal.
◦ No occlusal steps
◦ More conservative

20. TUNNEL PREPARATION
• Joins an occlusal lesion with proximal lesion by
means of prepared tunnel under the involved
marginal ridge.
• Marginal ridge intact.

21. THANK YOU