Effect of dentin pretreatment with mild acidic HOCl solution on microtensile bond strength and surface pH

Abstract

Objectives To evaluate the pretreatment effect of mild acidic HOCl solution on the microtensile bond strength (μTBS) of a two-step self-etch adhesive to dentin and the alteration of dentin surface pH. Methods Thirty-nine flat ground coronal dentin specimens were divided into one control group and 12 experimental groups, which were treated with 6% NaOCl or 50, 100 and 200 ppm HOCl (Comfosy ®) solutions for 5, 15 and 30 s. After rinsing with running water for 30 s, all the dentin surfaces were bonded with Clearfil SE Bond according to the manufacturer's instructions. After 24 h water storage, the bonded specimens were sectioned and trimmed to an hourglass shape with a cross-sectional area of approximately 1.0 mm 2 and then subjected to the μTBS test. Thirty-six mid-coronal dentin discs were used for surface pH measurement. Dentin surface pH with or without pretreatment was examined using a pH-imaging microscope (SCHEM-100). The μTBS data were analyzed by one-way ANOVA (Dunnett's T3) and the surface pH data were analyzed by non-parametric statistics (Mann–Whitney U-test). Results Pretreatment with Comfosy ® at concentrations of 50, 100 and 200 ppm did not significantly affect μTBS regardless of the application time compared with the control group, however the 100 and 200 ppm Comfosy ® groups showed significantly lower surface pH values. For the NaOCl pretreatment groups, a longer application time significantly decreased the μTBS and increased the surface pH values compared to the control group. Conclusions The 50 ppm Comfosy ® pretreatments for 5, 15 and 30 s did not affect the μTBS of the two-step self-etch adhesive to dentin and dentin surface pH.