Comparison of the Micro-Tensile Bond Strength of Composite Resin Restoration in Micro- and Nano-hybrid Composite Resins using Different Interfacial Materials

Abstract

Micro-tensile bond strength of new to old composite in micro-and nano-hybrid composites was studied using two interfacial materials of composite flow and silane-bonding compound in samples prepared using aluminum generator in an in vitro manner. Sixty samples prepared after one month of aging process, were divided into three groups: A (nanohybrid to nanohybrid), B (microhybrid to microhybrid) and C (nanohybrid to microhybrid) (20 samples for each group); each group was again divided into 4 subgroups: in the subgroup 1, flow composite and in subgroup 2, silane-bonding compound, were used for bonding new to old composite after sandblasting process. The two subgroups were also labeled as positive controls (integrated nanohybrid and microhybrid composite for groups A and B, and half nanohybrid for group C) and negative controls (bonding old to new composite without interfacial mediums). The prepared specimens were divided into 1 mm pieces and the micro-tensile bond strength of each piece was measured and recorded using the Universal Testing Machine. Data analysis was done using SPSS 17 software and P-value less than 0.05 was considered as significant. The highest and lowest micro tensile bond strengths in all the studied groups belonged to the positive and negative control subgroups, respectively. Also, in all the groups, the subgroup in which silane-bonding compound was used as interfacial material had significantly stronger bond strength than the composite flow. In a general comparison between the groups, group C showed better results than group B and group B showed better results than group A (P < 0.001). The results of this study show that the repair of old composite with the help of silane-bonding is the best way to increase bond strength of the composite, and also, the nanohybrid composite showed a weaker repair-ability as compared to the micro hybrid composite.