Micro-shear bond strength of adhesive systems to cementum

Purpose: To investigate the micro-shear bond strength of current adhesive systems to human cementum and compare the results with those to dentin. Methods: Two commercially available two-step adhesive systems were investigated; a self-etching primer system (Clearfil SE Bond) and a total-etch wet bonding adhesive system (Single Bond). The cementum and dentin surfaces were chosen from the mesial surfaces of extracted human molars and then bonded with each adhesive system. A micro-shear bond test was employed to evaluate the bond strength in this study. In addition, the etched cementum or dentin surfaces without any adhesive and the bonded interfaces between the adhesive and the cementum or the dentin were studied morphologically using scanning electron microscopy (SEM). Results: No significant differences were found between the adhesive systems used (P> 0.05). However, both adhesive systems showed significantly lower bonding to cementum than to dentin (P< 0.05). The relatively lower bond strengths to cementum probably resulted from the existence of coarse collagen fibers, which may cause less or inhomogeneous penetration of resin monomers into the etched zone.