Influence of matrix and insertion technique on the microleakage and microhardness of posterior composite restorations

This study sought to evaluate how the matrix and insertion technique affected microleakage and microhardness of posterior composite restorations. Class II preparations with the gingival margin in cementum were performed in 60 bovine teeth and divided into two groups: transparent matrix and reflective wedge (Group T) (n=20) and metallic matrix and wood wedge (Group M) (n=40). Cavities were restored and specimens were isolated with nail varnish, immersed in 0.2% Rhodamine B, and sectioned. Microleakage was evaluated under magnification (20x) and data were analyzed with one-way ANOVA. Microhardness was assessed at 1, 2, and 3 mm from the gingival wall and data were analyzed with two-way ANOVA. No significant difference was observed in terms of leakage. Significant differences were observed in terms of hardness for both factors, although no interaction was noted. It was concluded that the insertion technique had no influence on microleakage and that using a metallic matrix with oblique increments provided the highest hardness. There was no correlation between these two variables.