RESUMEN
OBJECTIVE: The objective of this study was to determine the ability of a calcium sodium phosphosilicate (NovaMin) particulate to occlude dentin tubules, and to characterize the nature of the occlusion through a number of in vitro studies. METHODS: Four experiments were designed to demonstrate the ability of NovaMin to 1) rapidly occlude tubules, 2) remain on the dentin surface in the face of acid challenges, and 3) form a biologically stable hydroxycarbonate apatite layer on the surface of dentin. Bovine dentin samples, polished to 1200 grit silicon and etched in 40% w/w o-phosphoric acid solution for 15 minutes to remove the smear layer, were employed in all four experiments. Four different experimental techniques were used to evaluate the effects of NovaMin and other marketed calcium-based products on tubule occlusion in 1) a single-treatment model, 2) a 10-day acid challenge cycling model to evaluate tubule occlusion, 3) a 10-day acid challenge cycling model to evaluate changes in surface hardness, and 4) a calcium-release model. Samples were assessed for tubule occlusion by scanning electron microscopy, surface mineralization by microhardness, and calcium release by inductively coupled mass spectroscopy. RESULTS: For the single-treatment model, statistical analysis showed that all treatment groups had statistically fewer open tubules than the control group (untreated; p < 0.001), and that the NovaMin group occluded significantly more tubules than the Quell group (p < 0.001). For the cycling models, after a one-time brushing with the NovaMin (SootheRx) dentifrice, significantly fewer open tubules were visible compared to the untreated control (p < 0.001). After the 10-day cycle, there were few visible open tubules on the samples treated with SootheRx, a significant reduction when compared to the control samples (p < 0.001). The hardness of dentin treated with NovaMin during the 10-day cycle was significantly greater than sound and demineralized dentin (p < 0.001). The calcium-release model demonstrated NovaMin-based dentifrices released less calcium initially compared to the other treatment groups. After four hours, a higher release of calcium was observed that was sustained over 24 hours. CONCLUSION: NovaMin adheres to an exposed dentin surface and reacts with it to form a mineralized layer. The layer formed is resistant to acid challenges and is mechanically strong. The continuous release of calcium over time is suggested to maintain the protective effects on dentin, and provide continual occlusion of the dentin tubules.