Effect of Sol–Gel-Derived Bioactive Glass-Containing Dentifrices on Dentin Surface Microhardness and Mineral Deposition

Exposed dentin is vulnerable to demineralization and hypersensitivity. Bioactive glass (BAG) is incorporated into dental materials to promote apatite deposition, but its effects relative to a BAG-free formulation remain unclear. This study evaluated dentifrices containing 0, 0.3, 0.6, and 1.0 wt% sol–gel-derived BAG (BG0, BG3, BG6, and BG10, respectively) on acid-etched human dentin. Specimens were brushed daily for up to 6 weeks and stored in artificial saliva. Surface microhardness was assessed on two specimens per group, and field-emission scanning electron microscopy and X-ray diffraction were assessed qualitatively. Microhardness changed over time (p = 0.0001); however, the concentration effect and concentration-by-time interaction were not significant (p = 0.202 and p = 0.538, respectively). Mean microhardness rose in all groups, including BG0. However, BG0 showed no detectable surface deposits or recovery of apatite-related reflections. In contrast, the BAG-containing groups showed surface deposits, partial tubule occlusion, and increasingly prominent apatite-related reflections. Surface hardness recovery and detectable deposition were therefore dissociable. Under these conditions, BAG was associated with surface precipitation and tubule occlusion on acid-etched dentin. These findings do not establish remineralization of the dentin matrix, a concentration-dependent effect, or an optimal BAG concentration.