Chlorhexidine and ethanol-wet bonding on bond durability to caries-affected dentin

Abstract

OBJECTIVE: Degradation of resin-dentin bond over time is a major problem in adhesive dentistry. Though clinically relevant, bonding to caries-affected dentin is not studied extensively. This laboratory study evaluated the synergistic effect of ethanol-wet bonding (EWB) and chlorhexidine (CHX) on bond durability of hydrophobic adhesive to caries-affected dentin. METHOD: Dentin surfaces of molars were etched after removal of coronal caries and were randomly allocated to four groups (n=12). In groups 1 and 2, dentin surfaces were saturated with either 2ml of 100% ethanol or 2ml of ethanol incorporated with 2% CHX for 60s. In groups 3 and 4, dentin surfaces were saturated with either 15µL of distilled water or 15µL of distilled water incorporated with 2% CHX for 60s. Two coats of primer (50wt% of ethanol and 50wt% of hydrophobic resin) followed by resin was applied and light-cured for 40s. Resin-composite build-ups were performed and bonded specimens were sectioned (n=8) to composite-sound dentin and composite-caries-affected dentin beams after 24h for bond strength testing. Half of the specimens were tested immediately and the remaining was tested after 12 months’ aging in artificial saliva. Bond strength data was analyzed using 3-way ANOVA and Student-Newman-Keuls tests. Interfacial nanoleakage was evaluated after 24h and 12 months using SEM and data were analyzed using chi-squared test. RESULT: The effects of dentin substrate, rewetting and time on bond strength were significant (p<0.05). Bond strength to sound dentin was significantly higher than caries-affected dentin at both time periods. Addition of 2% CHX to EWB significantly (p<0.05) preserved bond strength to sound and caries-affected dentin after 12 months. Compared to EWB alone, bonded interfaces from EWB+CHX group showed less interfacial nanoleakage after 12 months. CONCLUSION: Incorporation of chlorhexidine to ethanol-wet bonding has a synergistic effect on preservation of bond to both sound and caries-affected dentin after 12 months.