Effect of resin composite substrate and adhesive system formulations on shear bond strength of repaired composite - An in Vitro study

Abstract

Defects due to wear, fractures or discoloration can be treated successfully by repairing, thus avoiding over-treatment by total replacement that may endanger the pulpal health. exploration of failure gives idea whether to repair or not. Repair is removal of the defect, cavity assessment in which extension of defect and remaining tooth structure are evaluated. Repair is a minimally invasive method with less chair-side time and less risk of iatrogenic damage to adjacent teeth that helps to preserve intact tooth structure and enhance survival of the restoration. Repair of resin composite restorations is generally preferred over total replacement as it is also more cost-effective. The major goal of composite repairs is how to achieve a strong and durable bond between the existing and repair composite materials. In repairs, the durable and reliable adhesive joint between the substrate and the repair composite is crucial for clinical success. Attempts to develop composite repair primers have been made, but the bonding of the new composite to the old composite substrate remains problematic. Aged restorations do not contain an unpolymerized surface layer, several methods have been suggested to enhance the composite to composite adhesion such as roughening, etching surface with acidulated phosphoric acid air-borne particle abrasion, therefore surface treatment plays a key role in the repair of composite restorations. Such treatments remove the aged surface layer of the existing composite restoration and create irregularities, which increase the surface wettability, roughness and total surface area.