Scrubbing Effect of Self-etching Adhesives on Bond Strength to NaOCl-treated Dentin

Purpose: To evaluate the scrubbing effect of self-etching adhesive systems on the microtensile bond strengths to sodium hypochlorite-treated dentin. Materials and Methods: The occlusal surfaces of 36 extracted human third molars were horizontally cut to expose sound dentin. The dentin surfaces of the teeth were treated with 6% NaOCl aqueous solution for 30 s or none. After water rinsing for 10 s and air drying, a 2-step (Clearfil Protect Bond) or 1-step (Clearfil S3 Bond or Bond Force) self-etching adhesive was applied with or without a scrubbing technique, and resin composite (Clearfil AP-X) crowns were built up. The bonded specimens were stored in water for 24 h and then subjected to the microtensile bond test at a crosshead speed of 1.0 mm/min. Data were analyzed using three-way ANOVA and Bonferroni multiple comparisons (p 0.05). Results: The NaOCl-treated dentin exhibited significantly lower bond strength with the tested self-etching adhesive systems than did the normal dentin (p 0.05). Using a scrubbing technique for the tested self-etching adhesive systems significantly improved the µTBS to NaOCl-treated dentin (p 0.05), whereas there was no significant difference in µTBS to normal dentin between a scrubbing and nonscrubbing technique (p > 0.05). Conclusion: Using a scrubbing technique for applying self-etching adhesive systems to NaOCl-treated dentin was effective in improving the compromised bonding. Keywords: sodium hypochlorite, scrubbing, dentin, bond strength, adhesives