Presentation on theme: " There were considerations regarding various properties of composites for successful composite restoration to be done. These properties generally require."— Presentation transcript:
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 preparationApplication of the material Introduction:
Cavity preparations should be conservative as possible. The extent of the preparation is usually determined by : SizeShapeLocation 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 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)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.
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:
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) Sandpaper disc degree of abrasive depend on the amount of excess 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 surface Should be curved over the restoration.
7) Rubber polishing point 8) Aluminum oxide polishing paste 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: