Effect of 2% Chlorhexidine on Resin Bond Strength and Mode of Failure Using Two Different Adhesives on Dentin: An In Vitro Study

AIM: To evaluate the shear bond strength and failure mode of total-etch and self-etch bonding agents on human dentin with and without application of 2% chlorhexidine gluconate (CHX). MATERIALS AND METHODS: Eighty extracted premolars were chosen and stored in 10% formalin until use. Samples were mounted in cold cure acrylic resin and the occlusal enamel perpendicular to long axis of each tooth was removed using a low-speed diamond saw under water coolant. The prepared teeth were randomly divided into four groups of 20 samples each according to the adhesive system used. Groups 1 and 2 were the control group in which total-etch and self-etch adhesives were applied as per manufacturer’s instructions, Groups 3 and 4 were the experimental groups in which 2% CHX was applied and blot dried prior to the application of total-etch and self-etch adhesives. A custom-designed rig was fabricated to place composite on samples. The customized rig comprised a cylindrical mold with height of 3 mm and internal diameter of 2.5 mm. Resin was placed in increments of 1 mm and was cured after each increments. After the composite placements, samples were placed in distilled water at 37°C for 24 h. The samples were then thermocycled between 5°C and 55°C in water with a dwell time of 30 s in each temperature to a total of 10,000 cycles. The shear test was performed using universal testing machine and fracture modes were evaluated using stereomicroscope. RESULTS: Both the experimental total-etch and self-etch groups showed better shear bond strength than the control groups, which was statistically significant, and also the least mode of failure at the adhesive interface was observed in both the experimental groups. CONCLUSION: 2% Chlorhexidine gluconate effectively improved the shear bond strength and helped maintaining the durability of adhesive interface in both total-etch and self-etch adhesives.