onlays - shabeelpn

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MOD ONLAYS

INDICATIONS

Broken down teeth with intact buccal and lingual cusps

MOD restorations with wide isthmus

As a post endodontic restoration

To correct the occlusal plane of a tilted tooth

CONTRA INDICATIONS

Patients with high caries rate

Young patients

Teeth with short clinical crown height

INITIAL PREPARATION

1. OCCLUSAL REDUCTION

FIRST STEP IS THE REDUCTION OF THE CUSPS

WHICH IMPROVES THE

ACCESS AND VISIBILITY FOR SUBSEQUENT STEPS

IN TOOTH PREPARATION.

EFFECIENCY OF THE CUTTING INSTRUMENT AND

THE AIR-WATER COOLING SPRAY.

IT IS EASIER TO ASSESS THE HEIGHT OF THE

REMAINING CLINICAL CROWN OF THE TOOTH.

USING THE NO.271

CARBIDE BUR HELD

PARALLEL TO THE LONG

AXIS OF THE CROWN,

PREPARE 2 mm DEEP

PULPAL FLOOR ALONG

THE CENTRAL GROOVE.

THE OCCLUSAL

PREPARATION IS

EXTENDED FACIALLY

AND LINGUALLY JUST

BEYOND THE CARIES TO

SOUND TOOTH

STRUCTURE, TO VERIFY

NEED FOR CUSP

CAPPING.

WITH THE SIDE OF THE

NO.271 CARBIDE BUR,

PREPARE UNIFORM 1.5 mm DEEP DEPTH CUTS

ON THE REMAINING

OCCLUSAL SURFACE.

THEY ARE USUALLY

PLACED ON THE CREST

OF THE TRIANGULAR

RIDGES AND IN THE

FACIAL AND LINGUAL

GROOVE REGIONS.

THE DEPTH CUTS

SERVES AS GUIDES FOR

THE AMOUNT OF

REDUCTION.

CUSP REDUCTION IS

COMPLETED WITH THE SIDE

OF THE NO.271 BUR, AND

THE REDUCTION SHOULD

REFLECT THE GENERAL

TOPOGRAPHY OF THE

ORIGINAL OCCLUSAL

SURFACE.

SHOULD NOT ATTEMPT TO

REDUCE THE MESIAL AND

DISTAL MARGINAL RIDGES AT

THIS TIME( TO AVOID

HITTING ADJACENT TOOTH).

THE GINGIVAL-TO-OCCLUSAL

DIVERGENCE OF THESE

PREPARATION WALLS

SHOULD RANGE FROM 2-5 degrees DEPENDING ON

THEIR HEIGHTS.

2. OCCLUSAL STEP

AFTER CUSP REDUCTION,

THERE SHOULD BE A 0.5 mm

DEEP OCCLUSAL STEP IN THE

CENTRAL GROOVE REGION

BETWEEN THE REDUCED

CUSPAL INLCINES AND THE

PULPAL FLOOR.

OCCLUSAL STEP IS EXTENDED

FACIALLY AND LINGUALLY

BEYOND THE CARIOUS AREAS

AND THE WALLS SHOULD GO

AROUND THE CUSPS IN

GRACEFUL CURVES THEN

EXTENDED MESIALLY AND

DISTALLY TO EXPOSE THE

PROXIMAL DEJ IN

ANTICIPATION

OF PROXIMAL BOXING.

3. PROXIMAL BOX

CONTINUING WITH NO.271 CARBIDE BUR A PROXIMAL

DITCH IS PREPARED.

THE MESIODISTAL WIDTH OF THE DITCH SHOULD BE

0.8 mm AND PREPARED APPROX. TWO-THIRDS AT THE

EXPENSE OF DENTIN AND ONE-THIRD OF ENAMEL.

IDEAL EXTENSION GINGIVALLY OF A MINIMAL

CAVITATED LESION ELIMINATES CARIES ON THE

GINGIVAL FLOOR AND PROVIDES 0.5 mm CLEARANCE

OF THE UNBEVELED GINGIVAL MARGIN WITH THE

ADJACENT TOOTH.

FINAL PREPARATION

1.

REMOVAL OF THE

INFECTED CARIOUS

DENTIN AND

DEFECTIVE

RESTORATIVE

MATERIALS ON THE

PULPAL AND AXIAL

WALLS.

A CEMENT BASE CAN

BE GIVEN IF IT IS

INDICATED.

2.

PREPARATION OF

BEVELS AND FLARES.

A DIAMOND

INSTRUMENT IS USED

TO PLACE COUNTER

BEVELS ON THE

REDUCED CUSPS,

TO APPLY GINGIVAL

BEVELS AND TO

CREATE SECONDARY

FLARES ON THE

FACIAL AND LINGUAL

WALLS OF THE

PROXIMAL BOXES.

FISSURE THAT

EXTENDS SLIGHTLY

LINGUAL TO NORMAL

POSITION OF

COUNTER BEVEL MAY

BE INCLUDED BY

SLIGHTLY

DEEPENING

COUNTER BEVEL IN

FISSURED AREA.

AFTER BEVELILNG

AND FLARING SHARP

JUNCTIONS

BETWEEN THE

COUNTER BEVELS

AND THE

SECONDARY FLARES

ARE ROUNDED

SLIGHTLY.

LIGHTLY BEVEL

AXIOPULPAL LINE

ANGLE ALSO.

IF NECESSARY,

SHALLOW( 3 mm

DEEP) RETENTION

GROOVES MAY BE

CUT IN THE

FACIOAXIAL AND THE

LINGOAXIAL LINE

ANGLES WITH

NO.169 L CARBIDE

BUR.

COMPLETED MESIO OCCLUSO

DISTAL ONLAY PREPARATION

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