Effect of chlorhexidine incorporation into a self-etching primer on dentine bond strength of a luting cement.

OBJECTIVES: This study investigated the effect of incorporating chlorhexidine in a self-etching primer on the bond strength of an adhesive resin cement to dentine and on antibacterial activity.
METHODS: Experimental self-etching primers were prepared by adding chlorhexidine (CHX) diacetate to ED primer 2.0 (Kuraray Medical Inc.) to obtain chlorhexidine concentrations of 1.0 wt% and 2.0 wt%. Human occlusal dentine surfaces were conditioned for 30 s using the experimental primers or pure ED primer. Composite blocks were luted using Panavia F 2.0 (Kuraray Medical Inc.). After storage in water for 24 h, the bonded teeth were sectioned into 0.9 mm x 0.9 mm beams and stressed to failure in tension to examine microtensile bond strength (microTBS). Fractured surfaces were examined with a field-emission scanning electron microscopy (FE-SEM). The morphology of dentine surfaces that were conditioned with each primer was also observed under FE-SEM. An agar diffusion test was performed to examine the antibacterial effect of each primer against Streptococcus mutans and Enterococcus faecalis.
RESULTS: Addition of chlorhexidine to the primer had significant effects (p<0.001) on microTBS and antibacterial effect. No significant difference in microTBS was found between the groups that contained 0% and 1% chlorhexidine in the primer (p=0.095). Conversely, the group that contained 2% chlorhexidine showed significantly lower microTBS and pronounced cohesive failures within the thin layer of the primer.
CONCLUSIONS: Incorporation of chlorhexidine into ED primer 2.0 showed significant antibacterial activities. Conditioning with the 1% chlorhexidine-containing primer had no adverse effect on microTBS. Copyright 2010 Elsevier Ltd. All rights reserved.