Dentin pre-treatment on bond strength stability of self-etching and etch-and-rinse adhesive to bleached dentin

Abstract

This study aimed to evaluate the effect of using chlorhexidine or glutaraldehyde on bonding stability of self-etching and etch-and-rinse adhesives to bleached dentin. The occlusal surface of 80 third molars was abraded to exposed a flat medium dentin surface, which submitted to bleaching procedure using 20% hydrogen peroxide and sodium perborate for 14 days. Afterwards the dentin remained the same time in distillated water prior to adhesive procedures that was carried-out with a 3-step etch-and-rinse (Scotchbond Multipurpose Plus – SBMP) or a 2-step self-etching (Clearfil SE. Bond – CSE) adhesive. For each approach, the bleached dentin was treated with chlorhexidine, glutaraldehyde or non-treated prior to adhesive procedure. Non-bleached dentin was used as control. Composite cylinders were built-up over the adhesive covered dentin followed by parallel section of specimens to obtain 1-mm slices. The slices were trimmed to obtain hour-glass shape specimens with around 1.0 mm2 of bonding interface. Half of slices were submitted to microtensile bond strength test after 24h, while the remaining was stored in distillated water for 3 months prior to the same test. Failure mode was analyzed under optic microscopy. For SBMP, glutaraldehyde-treated dentin resulted in highest bond strength, maintaining the values after 3 months. For CSE, the highest bond strength was obtained on chlorhexidine-treated dentin. In general, it was observed bond strength reduction within water storage for both approaches. In conclusion, glutaraldehyde and chlorhexidine can be available treatments to improve the bond strength to bleached dentin.