Relative Performance of Antisensitivity Dentifrice, Rinse, and Oxalate Strips: An In Vitro Comparison of Common Global Over-the-Counter Products

The objective of this research was to evaluate the performance of a polyethylene strip coated with an oxalate-containing gel to occlude patent tubuli in human dentin. An in vitro model was adapted from the published literature to create a physiologically relevant microenvironment to study immediate and long-term effects of the strip. Observation techniques included scanning electron microscopy (SEM), SEM of ion-milled surfaces (SEM/FIB), and synchrotron-based x-ray microtomography. In addition, the reduction in hydraulic conductance induced by the strip was quantified. Significant deposition of crystalline oxalate was observed in treated dentin. Crystal density and occlusionary performance were found to be strong functions of strip application time and of the number of applications. Quantitative reduction in hydraulic conductance correlated well with crystal accumulation, also demonstrating a strong dependence on time and number of applications. The robustness of an oxalate crystal barrier formed with a single 10-minute strip application was tested over a 30-day period, during which dentin samples were subjected to a series of dissolution and mechanical challenges. Oxalate crystal density was shown to be modestly impacted, with substantial flow resistance maintained throughout the 30-day challenge period. The performance of an oxalate gel-coated strip is strongly affected by product-dentin contact time, producing an effective and durable occlusive barrier when applied as an adhesive strip.