efficacy of hydrophobic layer on sealing ability of dentin adhesive systems in class v composite resin restorations

background and aims. adhesive permeability is hindered by application of an additional layer of hydrophobic resin, which increases its concentration within the hydrophilic layer, reduces its affinity to water, and enhances its physical properties. the aim of the present study was to evaluate the effect of a hydrophobic layer on the microleakage of class v composite restorations using different adhesives. materials and methods. the adhesives including total-etch scotchbond mp and single bond, and the self-etch clearfil se bond and clearfil s3 bond were applied to 80 class v cavities in vitro on the buccal surface in cej and then were followed by hydrophobic resin (margin bond) in half of the cavities in each group (n=10). after restoration with microhybrid composite, z100 and immersion in fuchsine, the degree of microleakage was assessed. data were analyzed using the kruskal-wallis, man-whitney, and wilcoxon tests. results. the hydrophobic layer significantly reduced the microleakage of clearfil se bond and clearfil s3 bond only in dentin (p 0.05). conclusion. within the limitation of this study, only clearfil s3 bond could demonstrate the identical values of microleakage in enamel and dentinal margins.