Effect of Additional Surface Conditioning Methods and Adhesive Systems on Microleakage at Composite Repair Interfaces: An in Vitro Study

Repair of aged resin composites requires additional surface conditioning and an adhesive protocol capable of limiting interfacial leakage. This in vitro study evaluated three additional conditioning methods and two adhesive systems at aged composite–new composite repair interfaces. Ninety extracted posterior teeth were restored, thermocycled, and partially prepared with a diamond bur to create standardized repair surfaces. The surfaces then received additional diamond-bur roughening, 50-µm Al2O3 airborne-particle abrasion, or Er:YAG laser irradiation and were treated with Clearfil SE Bond or Clearfil Universal Bond Quick 2 (n = 15 per combination). After repair and additional thermocycling, maximum linear dye penetration was measured as the primary outcome; a derived ordinal grade was analyzed as a supportive, exploratory secondary outcome. A two-factor permutation analysis detected no significant effect of conditioning method (p = 0.142), adhesive system (p = 0.606), or their interaction (p = 0.341) on linear microleakage. In the ordinal proportional-odds analysis, the method effect was not statistically significant (p = 0.053); neither the adhesive effect (p = 0.763) nor the interaction (p = 0.754) was significant. Under the tested conditions, statistically significant differences in microleakage were not detected among the evaluated combinations.