Influence of CHX on Microtensile Bond Strength of Self-Etching Adhesives

Objective: The aim of the present study was to evaluate the inflence of different concentrations of chlorhexidindigluconate (CHX) on microtensile bond strength (mTBS) of two self-etching dentin adhesives (Futurabond NR, Bond Force) in vitro. Methods: 150 extracted third molars were included in this study. All teeth were specially prepared allowing the simulation of dentin perfusion. The specimens were randomly assigned to one of the ten groups of fifteen samples each: group F-C: Futurabond NR, control group (no CHX-application); F-0.2: immersion for five minutes in 0.2% CHX prior to bonding with Futurabond, F-2: immersion for five minutes in 5% CHX prior to bonding, F-5: immersion for five minutes in 2% CHX prior to bonding, groups B-C, B-0.2, B-2 and B-5 followed the same procedure with Bond Force as adhesive. MTBS was measured 15 minutes after application of the composite (Tetric Ceram) using an universal testing machine. Results: Statistical analysis showed a significant influence of the used dentin adhesive and the pre-treatment with CHX in different concentrations (p 0.001, ANOVA). The application of 2% and 5% CHX before bonding procedure (F-2, F-5, B-2, B-5) resulted in a significant reduction of mTBS compared to the untreated control groups (F-C, B-C) (p 0.05, Tukey's test). Between the controls and the 0.2% CHX-groups, no significant differences could be detected (p 0.05, Tukey's test). Pairwise comparison between Futurabond and Bond Force showed no significant differences in all groups (p 0.05, Tukey's test). Conclusions: Within the limitations of an in vitro investigation it can be concluded that CHX in higher concentrations affected the mTBS of both tested self-etching adhesive systems. Parole chiave: CHX, microtensile bond strength, self-etch adhesives