The Effect of Potassium Oxalate on Resin-Dentin Bond Durability

OBJECTIVE: The purpose of this study is to investigate the effect of tubule occlusion with potassium oxalate desensitizer on the microtensile bond strength of resin composite bonding to dentin after storage under simulated physiologic pulp pressure for 3 months. METHODS: Flattened occlusal dentin surfaces were obtained using the CNC specimen former (University of Iowa) on 30 extracted caries-free human molars. 37% phosphoric acid (Scothchbond Etchant, 3M ESPE) was applied and rinsed before one half of the occlusal surface per tooth was treated with potassium oxalate desensitizer (SuperSeal, Phoenix Dental) for 30 seconds with rubbing motion and then rinsed for 60 seconds leaving a visible moist surface for subsequent bonding. An etch & rinse 2-step adhesive (Single Bond Plus, 3M ESPE) was then applied followed by the application of resin composite (Z100, 3M ESPE). After 3 month storage under simulated physiologic pulp pressure at 15 cm H2O, specimens were sectioned and prepared for tensile testing at a cross head of speed 1 mm/min. RESULTS: Based on both paired-samples t-test and Cox proportional hazards survival analysis, the data provided strong evidence that microtensile bond strength in the group without potassium oxalate was significantly higher than the group with potassium oxalate (p<0.00001). CONCLUSIONS: Within the limitation of this in vitro study, it can be concluded that the use of potassium oxalate during etch&rinse bonding procedure can lower long-term microtensile bond strength. This finding is in direct contradiction to published short-term (24 hours) studies.