Desensitizer Effect on Composite Resin Dentin Shear Bond Strength

Tooth sensitivity with composite resin, is an unfortunate sequel for some patients. Desensitizing agents, used to prevent root sensitivity in teeth, are used under composite resin to prevent postoperative discomfort. Reports of their effects on bonding to dentin range from enhancement to degradation of the bond. Objectives: A comparison of four differing formulations of desensitizing agents 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. Gluma Desensitizer Powergel (GP), D/Sense Crystal (DC), Protect (PD) and Sensitive Pro-Relief (SR) were used according to manufacturers’ instructions to treat the flat, water-rinsed ground surfaces. An untreated group served as the quasicontrol (QC.) Using Single Bond (3M ESPE) unfilled resin and Herculite A2 composite resin (Kerr), cylindrical shear bond strength specimens, 20 per group, 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 GP (18.6 ± 2.8), DC (18.8 ± 2.6), PD (19.1 ± 3.3), SR (17.9 ± 3.5), and QC (19.9 ± 2.6). No statistical significance was found between groups (p = 0.46.) Conclusions: None of the tested desensitizing agents affected dentin bond strength in shear mode.  Acknowledgments: Northwestern University Mechanical Engineering, Centrix, Colgate-Palmolive, Patterson Dental.