there were considerations regarding various properties of composites for successful composite...

There were considerations regarding various properties of composites for successful composite restoration to be done.

These properties generally require specific technique in the restorative procedures

Cavity preparation Application of the material

Introduction:

Cavity preparations should be conservative

as possible. The extent of the preparation is

usually determined by :

Size Shape Location

of the defect

The extension should provide access for

vision and instrumentation. The strong bond which is developed

b/w: the etch enamel bonding agent

composite

This will promotes a strong indication for direct composites restoration to be used.

Developed by Buonocore in 1955. Technique consists of: 1. Applying a solution or gel of 30 – 50

% phosphoric acid to enamel for 20 sec.

to dentin for 30 sec

2. Thorough rinsing with water for 20 sec.

3. Drying the area with air free oil for

Acid Etch Phenomenon

5 Sec.

Acid Phenomenon (cont’n)

Acid solution affect the prismatic structure of the enamel by preferential removal of either

Prism core Prism Both Prism (I) Periphery core , periphery

(II) (III)

Acid Phenomenon

This process results in an enamel surface characterized by:

1) Numerous microscopic undercuts

2) Irregular surface in the enamel.

surface area for bonding. Provide a higher surface energy to

enhance wetting. contact angle good bonding

Demineralized porous enamel rod end (5-50Mm )

The resin can penetrate and produce mechanical tags (mechanical interlock)

Acid Etch Effect

Kind of acid used. Acid concentration. Etching Time. Form of etching (gel, semi gel,

solution) Rinsing Time. Way of Etching. Enamel Instrumented b / f etchant. Enamel of primary or permanent

teeth. Enamel is stained,demineralized or

flouridated.

Acid Etch Effect Depend onDepend on

Bonding agents - Resins with low viscosity used for the adhesion to enamel or dentin.

Acid etching + fluid resin bonding agent

the basis for the 1) Retention2) Marginal seal against microleakage of the composite resin restoration placed in cavity preparation involving enamel margins.

Enamel / Dentin Bonding System

Enamel/Dentin Bonding System

Dentin can be pre-treated like enamel to produce a surface that is more retentive.

Dentin bonding system consists of: 1. Conditioning agent - to remove a

smear layer (dentin debris) 2. Low viscosity hydrophilic resin primer to ensure optimal wetting and bonding to the hydrated dentinal

surface.

Enamel/Dentin Bonding System

3. Resin adhesive bonding agent [Unfilled resin (adhesive) BisGMA]

applied to dentin or

etched enamel

Acid Etching _ Remove 10Mm of enamel

surface

Conditioner _ Remove smear layer

Primer _ Stabilize collagen and facilitate

penetration of bonding resin

Factors Affecting the Adhesive Bond

Water.

Saliva.

Inadequate removal of acid etching.

Shade selectionCavity preparation

Etching liquid - for larger area 30 sec.

Gel • brush , syringe• untouched 15 sec • rinse 20 sec • dry 5 sec

Restorative Procedures:

Restorative Procedures: (cont’n) Bonding

• brush• light air• cure 20 sec.

Dry field if saliva or sulcular sweep age • reapply the acid

• contact the preparation

• etchant 10 sec• wash and dry.

Restorative Procedures: Matrix application aid in:

• placing composite resin

• contouring• reduce excess• minimize finishing time

Restorative Procedures:

Two types of matrices

• Polyester strip matrix

• Compound supported metal matrix

III, IV cavity preparations. Shape the strip to the desired tooth contour.

Restorative Procedures: Apply a wedge at the gingival margin:

1) Help to hold the strip in position.2) To provide slight separation of the teeth.3) To prevent a gingival overhang of the composite resin material.Wedge placed from the facial approach for lingual access cavities (vice versa).

Application of composite

using hand instrument

[plastic instrument]

Light cure 40 sec.

Good technique and experience in inserting composite reduce the amount of finishing required.

1) Flame shaped finishing bur removing excess and contouring

Finishing Technique for Composite

2)2)Sandpaper discSandpaper disc degree of abrasive degree of abrasive depend on the depend on the

amount of excess amount of excess to be removed to be removed..

3) Sof-Lex discs • for contouring and polishing • flexible • several diameter and abrasive textures.

4) Pop-on discs and mandrel• small diameter• placed, removed without the

need for proper orientation.• will fit into embrasure areas.• useful in contouring and

polishing gingival area.

5) No 12 surgical blade to remove inter proximal excess

6) Finishing strip (medium and fine) for • final contouring • finishing of proximal surfaceShould be curved over the restoration.

7)7) Rubber polishing pointRubber polishing point

8)8) Aluminum oxide polishing Aluminum oxide polishing pastepaste for final polishing..for final polishing..

Remove the rubber dam

Evaluate occlusion by having the patient close lightly on the articulating paper if excess is present, remove only a small

amount at a time and recheck.

Occlusion: