Effect of acid-etching on the bond strengths to sclerotic dentine

Objective: The objective of this study is to evaluate the effect of additional acid-etching on micro-tensile bond strength of self-etching adhesives to non-carious sclerotic dentine (NSD).Methods: Twenty-nine human canines and premolars with saucer-shaped noncarious cervical defects were cleaned, and twenty-four of them were randomly assigned to 3 groups of eight of each. Each tooth was cut in half longitudinally through the center of the cervical defect. Half of the cervical dentin was etched with 35% phosphoric acid for 15 s, and then bonded by adhesive. Other half were bonded with adhesive directly. The self-etching adhesives used were Contax (DMG), Clearfil S3 Bond(Kuarary)and Xeno III (Dentsply).A composite resin build-up (Chrisma) was formed on the adhesive layer. Matchstick-shaped samples through the bond interfaces were sectioned and then subjected to tensile bond test at a cross-head speed of 1. 0mm/min. Results: The micro-tensile bond strength of additional phosphoric acid-etching group was higher than that of non-phosphoric group in Contax and Clearfil S3 Bond (P<0.01). The additional phosphoric acid-etching showed no effect on Xeno III (P>0.05). Conclusions: Additional phosphoric acid etching method is beneficial to promote the bond strengths of some self-etching adhesives to non-carious sclerotic dentine.