الفهرس 
History of Composite
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Abstract
In recent years, the concept of minimally invasive dentistry suggests the repair of restorations instead of their replacement when clinically indicated. Restorations with minor damage, small fractures, signs of absence of marginal infiltration, and secondary caries may be repaired(1). When a restoration requires repair, it means that the composite resin has reached to the highest level of water saturation, which causes softening of the matrix, micro-crack formation, resin degradation and debonding of the filler-matrix interfaces(2). Dental resin based composites (RBCs), which are widely used in restoration of anterior and posterior teeth, still have limited lifetime. Dynamic changes in pH and temperature in the oral cavity because of diet, saliva and aging lead to degradation in the resin composite during clinical service(2, 3). In this case total replacement approach may weaken the tooth structure causing grinding sound tooth tissue or injuring the pulp tissue since in many cases remained restoration is clinically intact. Therefore, repairing the restorations may be another option for replacement(4). Many factors affect the bond strength between aged and new composite including surface characteristics(4), wettability(5),roughness , and the surface conditioning methods performed(4). To improve the adhesion between aged and new composite resins, different surface conditioning methods were developed and surface conditioning has an important impact on repair bond strength because the adhesive strength of composite to composite restorations decreases by 25% to 80% compared to their original strength(6).