The Effect of Pre-heating Silorane-based Composite Resin on Marginal Gap Formation of Class V Restorations

Statement of problem: Many efforts have been made to solve the problem of composite resin adaptation and reduce microleakage. Objective: The aim of the present study was to evaluate the effect of preheating of silorane-based composite resins before photo-polymerization on gap formation at the margins of Class V restorations. Materials and Methods: Standard Class V cavities were prepared on the labial surfaces of 46 sound bovine incisor teeth. The teeth were divided into two groups. In group 1, after application of the bonding agent of the silorane system, the cavities were restored with Filtek silorane-based composite resin stored at room temperature. In group 2, before restoring the cavities, the silorane-based composite resin was heated in a warm water bath at 54ºC for 10 minutes. After 48 hours of storage in distilled water, teeth were thermocycled and sectioned bucco-lingually. Then the gaps of tooth‒restoration interfaces in both incisal and gingival margins at three external, middle and internal areas were measured using a stereomicroscope. After calculation of means and standard deviations, data were analyzed with two-factor ANOVA at α=0.05. Results: The mean marginal gaps in non-preheated and preheated groups were 10.66±2.39 and 7.62±2.05 µm, respectively, with a statistically significant difference (P<0.001). However, the differences between the occlusal and gingival margins in each group were not significant (P=0.58). The interactive effect of preheating and margin type was not significant (P=0.10). Conclusions: Heating silorane-based composite resin before light curing resulted in decreasing the gap sizes at tooth‒restoration interfaces in Class V cavities