Composite Resin Material Part 11 Dr. Nesrien Ateyah

Introduction:  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

 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.

Acid Etch Phenomenon 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 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)

This process results in an enamel surface characterized by: Acid Phenomenon This process results in an enamel surface characterized by: 1) Numerous microscopic undercuts 2) Irregular surface in the enamel.

Acid Etch Effect  Provide a higher surface energy to enhance   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 Depend on  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.

Enamel / Dentin Bonding System  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) Retention 2) Marginal seal against microleakage of the composite resin restoration placed in cavity preparation involving enamel margins.

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.

Restorative Procedures:  Shade selection  Cavity preparation  Etching liquid - for larger area 30 sec. Gel • brush , syringe • untouched 15 sec • rinse 20 sec • dry 5 sec

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.

2) To provide slight separation of the teeth. 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).

 using hand instrument [plastic instrument]  Light cure 40 sec.  Application of composite  using hand instrument [plastic instrument]  Light cure 40 sec.

Finishing Technique for Composite  Good technique and experience in inserting composite  reduce the amount of finishing required. 1) Flame shaped finishing bur  removing excess and contouring

2)Sandpaper disc  degree of abrasive. depend on the. amount of excess 2)Sandpaper disc  degree of abrasive depend on the amount of excess to be removed.

4) Pop-on discs and mandrel 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.

6) Finishing strip (medium and fine) for • final contouring 5) No 12 surgical blade to remove inter proximal excess 6) Finishing strip (medium and fine) for • final contouring • finishing of proximal surface Should be curved over the restoration.

7) Rubber polishing point 8) Aluminum oxide polishing paste  for final polishing..

Occlusion:  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.

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