Effect of single step adhesives on the marginal permeability of Class V resin composites

This in vitro study evaluated the coronal and apical marginal microleakage of four self-etch, seventh generation adhesive systems. Sixty non-carious human molars were randomly assigned to four groups (n = 12). Class V cavities were prepared on the facial or lingual surface of each tooth with coronal margins in enamel and apical margins in cementum (dentin) at the cementoenamel junction. The preparations were restored using four self-etch adhesive systems (iBond, G-Bond, Xeno IV and Clearfil S3 Bond) and a control (no adhesive), followed by insertion of Gradia Direct microfilled hybrid resin composite. The teeth (specimens) were thermocycled 1,000 cycles, immersed in 1% methylene blue dye for 24 hours and invested in acrylic resin. The specimen blocks were then sectioned longitudinally, with dye penetration (microleakage) examined using a 20x binocular microscope. Coronal and apical margins were scored separately for microleakage using a 0-3 ordinal ranking system. Data were analyzed using non-parametric tests at a p < 0.05 level of significance. A comparison of adhesive and control groups at the coronal and apical margins revealed that significant (p < .0001) differences were exhibited. At the coronal margin, Xeno IV revealed significantly less leakage than the other adhesives, with Clearfil S3 Bond exhibiting significantly less leakage at the apical margin. Groups with no adhesive treatment (control) showed significantly greater leakage at both the coronal and apical margin locations. A Wilcoxon signed rank test showed no significant differences at the coronal compared to the apical margins of the four adhesive systems and control tested.