PRINCIPLES OF TOOTH PREPARATION

1. PRINCIPLES OF TOOTH PREPARATION
• BY AJAY RAJENDRA PATIL

2. WHAT IS TOOTH PREPARATION?
• Tooth preparation may be defined as the mechanical treatment of dental disease or injury to
hard tissue that restores a tooth to the original form.
•
• Tylman
•
• The mechanical preparation or the chemical treatment of the remaining tooth structure, which
enables it to accommodate a restorative material without incurring mechanical or biological
failure.
•
• Marzouk

3. PRINCIPLES OF TOOTH PREPARATION
BY SHILLINBURG
PRESERVATION
OF TOOTH
STRUCTURE
RETENTION
AND
RESISTANCE
STRUCTURAL
DURABILITY
MARGINAL
INTEGRUTY
PRESERVATION
OF
PERIDONTIUM

4. PRESERVATION OF TOOTH
STRUCTURES
• PRESERVATION OF ADJACENT TEETH
• PRESERVATION OF SOFT TISSUE
• PRESERVATION OF PULP
• CONSERVATION OF TOOTH STRUCTURES

5. PRESERVATION OF ADJECENT TEETH
• BY PREFERRING METALLIC BANDS
• BY A LAYER OF PROXIMAL ENAMEL RETAINED

6. PRESERVATION OF SOFT TISSUE
• BY CAREFUL HANDLING OF THE INSTRUMENTS

7. PRESERVATION OF PULP
• Vital pulp therapy is broadly defined as treatment to preserve and
maintain pulp tissue in a tooth that has been compromised by
caries, trauma, or restorative procedure.
• Dentin has excellent buffering capability to neutralize the effects of
cariogenic acids, and it insulates the pulp from temperature
increases during cavity preparation

8. CONSERVATION OF TOOTH
STRUCTURES
• PRESERVE THE REMAINING TOOTH STRUCTURES
• CONSERVATION GUIDELINES
• COVERAGE-PARTIAL VS COMPLETE
• MARGIN-SUPRAGINGIVAL VS SUBGINGIVAL
• PREPARATION OF TEETH WITH MINIMUM AXIAL WALLS

9. RETENTION AND RESISTANCE
• RETENTION-Retention in complete dentures refer to the ability of
that denture to resist displacement in a direction opposite the path
of insertion.
• Vertical forces are involved in retention e.g. sticky food gravity
chewing action and oral musculature tongue cheeks etc.

10. • RESISTANCE – RESISTANCE TO REMOVAL OF TISSUES FROM
TEETH

11. STRUCTURAL DISABILITY
• RESTORATION MUST CONTAIN BULK OF MATERIAL THAT IS
ADEQUATE TO WITHSTAND FORCES OF OCCLUSION.
• THIS BULK MUST BE CONFINED TO THE SPACE CREATED BY
THE TOOTH PREPARATION.
• ONLY THIS WAY THE OCCLUSION WILL BE HARMONIUS AND
AXIAL CONTOURS NORMAL.

12. • 1.OCCLUSAL REDUCTION
• 2.FUNCTIONAL CUSP BEVEL
• 3.AXIAL REDUCTION

13. • OCCLUSAL REDUCTION – ONE OF THE MOST IMPORTANT
FEATURES OF PROVIDING ADEQUATE BULK OF METAL AND
STRENGTH TO THE RESTORATION IS OCCLUSAL CLEARANCE

14. OCCLUSAL REDUCTION
• THE BASIC INCLINED PLANE PATTERN OF THE OCCLUSAL
SURFACE DUPLICATED TO PROVIDE ADEQUATE CLEARANCE
WITHOUT OVERSHORTNING THE PREPARATION.
THE FLAT OCCLUSAL SURFACE MAY OVERSHORTEN THE
PREPARATION

15. FUNCTIONAL BEVEL CUSP
• THE INTEGRAL PART OF OCCLUSAL REDUCTION IS
FUNCTIONAL CUSP BEVEL.
• THE WIDE BEVEL PLACED ON THE FUNCTIONAL CUSP
PROVIDES SPACE FOR AN ADEQUATE BULK METAL IN AN AREA
OF HEAVY OCCLUSAL CONTACT.

16. FUNCTIONAL CUSP BEVEL
• Lack of functional cusp bevel may produce several problems :
•
• 1. Can cause a thin area or
• perforation.
• 2. May result in over contouring
and poor occlusion
• 3. Over inclination of the buccal surface will destroy excessive tooth structure reducing retention.

17. AXIAL REDUCTION
• Plays an important role in securing space for an adequate thickness of the
restorative material.
• Inadequate axial reduction will have thin walls subject to distortion or result
in over contouring the axial surface which could lead to periodontal
problems.

18. • THANK YOU