CAVITY PREPARATION

PRINCIPLES & PROCEDURESPresented by

CULEEN

BARAPON

PYRRHIC

CANCINO

CAVITY PREPARATION

“a surgical procedure that removes caries and excises the tooth tissue in order to develop the mortise form that will support and retain the restorative material”

“the orderly operating procedure required to establish in a tooth the biomechanically acceptable form necessary to receive and retain a restoration”

COMPONENTS

Cavity

Wall

one of the enclosing sides of a prepared cavity

AxialWall

Wall near the pulp and parallel to the long axis of the tooth

Pulpal

Wall

Wall near the pulp and perpendicular to the long axis of the tooth

LineAngl

e

Angle formed by the junction of two walls along a lineCavo-

surfaceMargin

Angle in a prepared cavity formed by the junction of the cavity wall and the external tooth surface

PointAngl

e

Angle formed by the junction of three walls

at a common point

Undercut

Portion of the prepared cavity

confined by walls that converge

toward the surfaceRetention

Groove

A linear channel within a cavity

preparation

Dovetail

A widened or fanned out portion of a prepared cavity

THE PRINCIPLES

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Outline Form

Resistance Form

Retention Form

Convenience Form

Caries Removal

Finish of the Cavity

Walls

Cavity Debridemen

t

OUTLINE FORM

“The shape of the area of the tooth surface INCLUDED WITHIN THE CAVOSURFACE MARGINS of the prepared cavity”“The locations that the PERIPHERIES of the completed tooth preparation WILL OCCUPY on tooth surface”

“The PERIMETER of tooth preparation in width, length and depth dimensions”

THE OUTLINE FORM

Factors to be considered

Areas to be Included

1. Access to the lesion

2. Extent of the lesion

3. Extent of the caries- susceptible tooth surface area

4. Location and extent of developmental grooves

5. The restorative material to be used

6. Esthetic factors7. Functional

requirements of the restoration

1. Area of the carious lesion

2. The adjacent deep, non-coalesced enamel defects

3. All undermined, unsupported enamel

RESISTANCE FORM

“The shape given to the preparation that enables the restoration and the remaining tooth structure TO WITHSTAND MASTICATORY STRESS”

“The shape given to the preparation TO PREVENT FRACTURE of either the restoration or tooth during insertion of the material or during function”

THE RESISTANCE FORM

Prevent Fracture of Restoration

Prevent Fracture of Tooth

1. Occlusal Outline Area- box shape, flat floors

2. Correct Treatment of Line Angles – rounded

3. Adequate Reduction for Bulk and Pins

4. Correct Carving

1. Occlusal Outline Area

2. Removed Undermined Enamel

3. Removed Fragile Cusps

4. Correct Treatment of Line Angles - rounded

RETENTION FORM

“The shape of the internal aspect of a prepared cavity to PREVENT DISPLACEMENT OF THE RESTORATIVE MATERIAL”

“The form given to the tooth preparation, especially its detailed anatomy and general shape, which enables the restoration, that it will accomodate, TO AVOID BEING DISLODGED BY MASTICATORY LOADING”

THE RETENTION FORM

Auxiliary MeansPrincipal Means

1. Grooves2. Internal boxes3. Posts4. Pins5. Triangular areas6. Etching or acid

conditioning7. Cement

1. Frictional Retention

2. Elastic deformation of dentin

3. Inverted truncated cones or undercuts

4. Dovetail

CONVENIENCE FORM

“The shape or form of the cavity that ALLOWS ADEQUATE VISION, ACCESSIBILITY, AND EASE OF INSTRUMENTATION during cavity preparation as well as insertion of the restorative material”

“That shape given to a tooth preparation or tooth modifications added to the preparation or its instrumentation, which ENABLES THE RESTORATION TO BE COMPLETED CONVENIENTLY”

THE CONVENIENCE

FORM

Other Modes to Obtain

Convenience Form

1. Modifications in tooth preparation

2. Instrument modification

3. Separation

Ideally, a tooth preparation fulfilling all the requirements for outline, resistance, and retention forms will be convenient to instrumentation.

The most effective way is by proper control of the field of operation and by adequate training and familiarity with the armamentarium

CARIES REMOVAL

“The MECHANICAL ELIMINATION OF CARIOUS DENTIN AND DEBRIS from cavity preparations”

“The mechanical and/or chemical actions resulting in COMPLETE ELIMINATION OF THE DISEASED, NONREPARABLE PORTIONS OF DENTIN”

CARIES REMOVAL

Removal of Caries

Acute caries – using the broadest discoid/spoon excavator

Chronic caries – using large round bur preferably dull

REMOVAL OF DENTIN DEPENDS ON TWO

CONDITION:AFFECTED

DENTIN• does not contain microorganism• can be remineralized by restorative means• it is accepted to allow affected dentin to remain in prepared tooth

INFECTED DENTIN

• contains microorganism• cannot be remineralized by restorative means• it should be removed during cavity preparation

FINISH OF THECAVITY

WALL“Involves REFINING OF CERTAIN AREAS OF THE CAVITY WALL: the dentin portion, the enamel portion and the cavosurface margin”“The ‘CONFIGURATION’ OF THE ENAMEL WALLS is the shape, dimension, location, and angulation of enamel components in a final tooth preparation”“To PROVIDE THE BEST POSSIBLE MARGINAL SEAL AND MAXIMUM STRENGTH to both the tooth and the restorative material”

Enamel wall must rest upon sound dentin

FINISH OF THE CAVITY WALL

The enamel rods which form the cavosurface

angle must have their inner ends resting on

sound dentinThe rods which form the cavosurface

angle must be supported, or be resting, on sound dentin and their

outer ends must be covered by the restorative material

The cavosurface angle must be so trimmed or bevelled that the margins will not be exposed to injury in condensing the restorative material against it

CAVITY DEBRIDEMENT

“Final step involving the use of explorer, air and water spray, and cotton pellets to REMOVE DEBRIS FROM THE CAVITY PREPARATION”

“It consists of FREEING ALL ANGLES AND SURFACES OF DEBRIS and often includes medication and insulation procedures.

1. Freeing of all preparation walls, floors and margins from enamel and dentin chips

2. Drying the preparation walls, floors and margins

3. Sterilization of preparation walls and floors.

CAVITY DEBRIDEMENT

Objectives

Water, air, or combinations of air-water jets

Dry cotton pellets

Cavity cleaners

Scraping walls, floors and margins

Using preparation disinfectant

Using 10% EDTA Solution

METHODS

FOR AMALGAM

CAVITY PREPARATIONs

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