Effect of Chlorhexidine concentrations on micro-shear bond strength of self-etch adhesive to normal and caries-affected dentin

Purpose: To evaluate the effect of different Chlorhexidine concentrations on bond strength of resin composite to normal and caries-affected dentin using a self-etch primer adhesive. Methods: Thirty carious human molars were ground to expose flat dentin surfaces containing caries-affected surrounded by normal dentin. The teeth were divided into three groups. One group received no Chlorhexidine pretreatment (control). The second and third groups received 2% or 5% Chlorhexidine pretreatments, respectively before applying the self-etch primer adhesive (Clearfil SE Bond). Resin composite was applied to caries-affected dentin and to normal dentin on the same tooth with the aid of polyethylene tubes (0.9 mm diameter and 0.7 mm height). For micro-shear bond strength testing, each tooth was secured in a specially designed attachment jig to hold the specimens to the universal testing machine. Load was applied by the testing machine through a wire loop adjusted to the bonded interface at a crosshead speed of 0.5 mm/minute. Micro-shear bond strength was calculated and mode of failure was examined with a x40 stereomicroscope. Results: Statistical analysis revealed insignificant differences between control, 2% and 5% Chlorhexidine pretreatment for normal as well as for caries-affected dentin groups. Also, there were insignificant differences in bond strength values between normal and caries-affected dentin for each treatment modality. Adhesive failure was the most common mode or failure.