Effect of matrix systems and polymerization techniques on microleakage of Class II resin composite restorations

This study investigated the effect of different sized light curing tips (2 mm and 11 mm) with curing techniques associated with different matrix systems (Mylar with reflective wedge and metal with wooden wedge) on microleakage of a posterior resin composite material (P-50) placed using a bonding agent (Scotchbond 2). Eighty Class II mesial and distal slot preparations (40 with enamel gingival margins and 40 with dentin gingival margins) were randomly divided into four equal groups: 1) metal matrix, large tip; 2) Mylar matrix, light emitting wedge, large tip; 3) Mylar matrix, light emitting wedge, small tip; 4) metal matrix, small tip. Three-way ANOVA indicated no statistical differences among groups using small and large curing tips. The results showed significantly more leakage (alpha = 0.05) in the dentin gingival cavosurface margin groups than the enamel cavosurface margin groups. The results also showed significantly greater leakage in the polymerization procedures associated with the metal matrix groups (alpha = 0.05) compared to polymerization procedures associated with the Mylar matrix groups.