Methods: Twenty-five patients received three Class I (occlusal) or Class II restorations performed with one of three restorative systems: Filtek Silorane Restorative System (FS); Adper Scotchbond 1 XT, a 2-step etch-and-rinse adhesive, with Filtek Z250 (XT); and Adper Scotchbond SE, a 2-step self-etch adhesive, with Filtek Z250 (SE). All materials were applied following the instructions of the manufacturer. Two independent observers evaluated the restorations at baseline, after 6 months and 1 year, according to the USPHS modified criteria. Kruskal-Wallis and Mann Whitney U tests were computed to compare the behavior of the restorative systems; Friedman and Wilcoxon tests were used to analyze the intra-system data (p<0.05).
Results: All restorations were evaluated at 1 year. FS and XT performed statistically similar at 1 year, but marginal staining for SE was statistically worse. Intra-system comparisons between baseline and 1 year also showed deterioration of marginal staining for SE, while a deterioration of the marginal adaptation was recorded for both SE and FS. XT was the only system for which there was no statistical change of the parameters measured in this study.
Conclusion: Both restorative systems using self-etch adhesives showed a tendency to worse marginal adaptation after 1 year of clinical use compared to baseline. Although the clinical performance of FS was demeed acceptable after 1 year, this study did not find any advantage of the silorane-based composite over the methacrylate-based composite. The low-shrinkage associated with FS may not be a determinant factor for clinical success.