effect of cyclic loading on microleakage of silorane based composite compared with low shrinkage methacrylate-based composites

background: there are many concerns regarding the marginal seal of composite restorations, especially when composite restorations are subjected to cyclic loading. the aim of this study was to evaluate the effect of cyclic loading on the microleakage of silorane based composite compared with low shrinkage methacrylate-based composites in class v cavities. materials and methods: in this in vitro study, class v cavities were prepared on the facial and lingual surfaces of 48 human premolars (96 cavities). the teeth were randomly divided into four groups of 12 teeth (24 cavities) each and restored as follows: group 1 (siloran system adhesive + filtek p90), group 2 (all bond se + aelite ls posterior), group 3 (futurabond nr + grandio), and group 4 (g-bond + kalore-gc). all the specimens were thermocycled for 2000 cycles (5–55°c) and then half of the specimens from each group, were load cycled. all teeth were immersed in 0.5% basic fuchsine dye, sectioned, and observed under a stereomicroscope. data were analyzed using wilcoxon test, kruskal–wallis, and mann–whitney u-tests. p < 0.05 was considered as signifi cant. results: in both unloaded and loaded groups, no statistically signifi cant differences were observed among four composites at the occlusal margin, but a signifi cant difference in gingival microleakage was found between aelite and silorane. occlusal and gingival microleakage was not affected by cyclic loading in none of the four restorative materials. conclusion: silorane did not provide better marginal seal than the low shrinkage methacrylate-based composites (except aelite). in addition, cyclic loading did not affect the microleakage of evaluated composite restorations. key words: composite resins, dental leakage, polymerization, silorane resins