Effect of chlorhexidine and ethanol wetbonding on immediate dentine bondstrength

Abstract

Objectives: This study examined the effect of adjunctive application of ethanol wet-bonding (EWB) and chlorhexidine (CHX) on immediate resin-dentine bond strength with hydrophobic adhesive. Methods: Flat dentine surfaces were prepared from twenty extracted non-carious human third molars. Dentine surfaces were etched with 35% phosphoric acid for 15 s, rinsed and blot-dried before bonding. The teeth were divided into four groups for bonding using EWB or EWB with 1%, 2% and 3% CHX incorporated in the final step of ethanol application. An experimental hydrophobic adhesive was prepared and applied to dentine surface and light-cured. Composite build-ups were performed using Filtek Z250 (3M ESPE). For microtensile bond strength (μTBS) evaluation, composite-dentine beams were stressed to failure at a crosshead speed of 1 mm/min. The μTBS data was analyzed using one-way ANOVA and Student-Newman-Keuls multiple comparison test. Representative fractured beams from each group were prepared for fractographic analysis under SEM.

Results: One-way ANOVA showed that the incorporation of CHX in EWB significantly affected (P<0.05) the μTBS of hydrophobic adhesive to dentine. No significant difference in μTBS was observed among EWB (30.12 ± 9.83 MPa), EWB/1% CHX (30.24 ± 5.65 MPa) and EWB/2% CHX (26.51 ± 7.34 MPa) groups. However, significant reduction (P<0.05) in μTBS was observed in EWB/3% CHX group (25.19 ± 6.25 MPa). The majority of failures in EWB, EWB/1% CHX and EWB/2% CHX groups adhesive and mixed failure involving the adhesive and composite interface; the failure mode was largely adhesive involving the adhesive-dentine interfaces.

Conclusions: The adjunctive application of 1% and 2% of chlorhexidine with ethanol wet-bonding has no adverse effect on the immediate resin-dentine bond strength.