Effects of a Universal Adhesive System and the Snow-Plow Technique on Microleakage of Class II Composite Restorations in Primary Molars.

Objectives: This study evaluated the effects of using a universal adhesive and application of a flowable composite by the snow-plow technique on microleakage of Class II composite restorations in primary molars. Materials and Methods: In this in vitro study, Class II cavities were prepared with their gingival margin at the cementoenamel junction in the proximal surfaces of 90 freshly extracted primary molars. The teeth were then assigned to 3 groups (n=30) for the application of a universal adhesive (Single Bond Universal) in total-etch and self-etch modes and a conventional etch-and-rinse adhesive (Single Bond 2). Each group was divided into 3 subgroups (n=10) for restoration without a flowable liner (control), application of a precured flowable liner, and using a flowable composite as liner by the snow-plow technique. After 1000 thermal cycles, the gingival margin microleakage was evaluated using the fluid filtration technique. Data were analyzed by two-way ANOVA and Tukey's test (alpha=0.05). Results: Type of adhesive, unlike liner application (P=0.579), had a significant effect on microleakage (P=0.01). Application of universal adhesive (whether in self-etch or total-etch mode) resulted in less microleakage than the conventional etch-and-rinse adhesive. There was no statistically significant difference between the two application modes of the universal adhesive (P>0.05). Conclusion: Application of Single Bond universal adhesive for composite restoration of primary molars may improve the marginal seal and decrease microleakage.