Antisensitivity Toothpastes Effect on Dentin Shear Bond Strength

Radicular wear of teeth often leads to sensitivity to thermal and mechanical stimuli. Commercial toothpaste products can ameliorate pain by occluding dentin tubules. Restoration of lost dentin also lessens pain from these wear defects. However, the effects of these dentifrices on bonding to dentin has received little investigation. Objectives: A comparison of three sensitivity preventive dentifrices, MI Paste (MI), Pronamel (PN) and Sensodyne (SD), on dentin bond strength in shear mode was conducted. Methods: Human 3^rd molars, immediately stored in a 1% Chloramine-T solution post extraction, served as the test medium. These teeth were ground to expose the occlusal dentin with a water-cooled, coarse grinding wheel and then mounted in PVC rings with dental stone. Using 180 – 320 grit wet silicon carbide abrasive paper, the surfaces were flattened. Three cohorts, each with 20 teeth, were brushed twice daily with a dentifrice/human saliva slurry and one quasicontrol (QC) cohort was brushed only with human saliva for 30 days. Using Single Bond (3M ESPE) unfilled resin and Herculite A2 composite resin (Kerr), cylindrical shear bond strength specimens were fabricated on the acid-conditioned prepared surfaces in accordance with manufacturers’ recommendations using the Ultradent jig system. After 7 days storage at 35°C and 100% relative humidity, the specimens were tested in shear mode to failure at 2 mm/min to failure and peak loads were recorded. Strength data was analyzed by ANOVA and the Tukey-Kramer HSD methods (α = 0.05.) Results: Shear strengths (MPa) were found to be MI (15.5 ± 3.0), PN (16.1 ± 2.4), SD (16.8 ± 2.4), and QC (19.7 ± 2.3). Statistical significance was found between groups (p = 0.02.) Conclusions: MI reduced dentin bond strength about 16% compared to PN and SD. Acknowledgment: Northwestern University Mechanical Engineering.