Transcript onlays - shabeelpn

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