A Comparative Evaluation of Microleakage of Two Low-Shrinkage Composites with a Conventional Resin Composite: an in Vitro Assessment

Statement of the problem: polymerization shrinkage stress in composite restorations may lead to microleakage. clinical methods such as using low-shrinkage composites have been suggested to overcome this problem; however, there are controversies about their efficiency in decreasing the microleakage. purpose: this in vitro study was conducted to compare the microleakage of two lowshrinkage resin composites with a conventional one. materials and method: fifty class v cavities of 2.5×3×2 mm (depth× length× width) were prepared in the buccal surfaces of intact bovine incisor teeth with the incisal margin on the enamel and gingival margin on the cementum. the teeth were randomly divided into 5 groups. in group 1, clearfil apx (conventional) with se bond was used in 2 layers (kuraray; japan). in group 2, gc kalore (low –shrinkage) with gc unifil bond was applied in one layer (gc company). in group 3, the material of group 2 was applied in two layers. in group 4, filtekp90 (low –shrinkage) with p90 system adhesive was applied in one layer (3m espe). in group 5, the materials of group 4 were applied in two layers. the samples were thermocycled and immersed in 0.5% fuchsin solution for 24h. the restorations were sectioned in buccolingual direction. then they were evaluated for microleakage by using a stereomicroscope and scored as 0, 1, 2, and 3 and then kruskal-wallis test was used (p< 0.05). results: the groups were not significantly different regarding the microleakage in the coronal and cervical margins (p< 0.423 and p< 0.212, respectively); however, the filtek p90 yielded the best results. in all groups, except group 5 (p= 0.018), the cervical margins had greater microleakage than the coronal margins. conclusion: the results suggested that low-shrinkage resin composites may not reduce the marginal microleakage. the proper use of conventional resin composites may offer comparable clinical results.