Influence of Chlorhexidine and Moisture Degree on Dentin Bond Strength

Objectives: The aim of this study was to evaluate the influence of aqueous solution of chlorhexidine digluconate 2%, applied to wet or dry bovine dentin tissue, on the bond strength of etch-and-rinse dental adhesives using the microtensile test under simulated pulpal pressure of 22 mmHg. Methods: The buccal surface of bovine incisors teeth were wet ground to obtain flat dentin surfaces. The teeth were randomly divided into four groups according to the adhesive systems: Scotchbond Multi-Purpose, Optibond FL, Single-Bond and Optibond Solo Plus. The teeth were submitted to different treatments: with or without 2% chlorhexidine applied on dry or wet dentin with different observation times (immediately and after 6 months storage in water). The solution of chlorhexidine was applied immediately after washing of acid. Regarding the degree of drying dentin, the variation occurred in the drying protocol after etching: blot-dried with absorbent paper (moist dentin) or dentin air-dried for five seconds (dry dentin). The specimens were restored with three independent horizontal increments of composite resin with 1mm thick each. The microtensile bond strengths were determined using a Universal loading machine (MTS 810, MTS Systems Corporation, Minneapolis, MN, USA) at a cross-head speed of 0.5 mm/min. The data were analyzed statistically by ANOVA and Bonferroni tests at P = .05. Results: Optibond Solo Plus showed statistical difference for the type of dentin and treatment with chlorhexidine. All adhesives systems showed higher bond strength to immediate microtensile test than after artificial aging. Conclusions: Only the adhesive Optibond Solo Plus suffered interference of treatment type of the substrate.