Effect of a 1.1% NaF toothpaste containing Sr/F-doped bioactive glass on irradiated demineralized dentin: an in vitro study.

Objective: Patients receiving head and neck radiation are at high risk for radiation caries. This study aimed to evaluate the remineralizing effects of an experimental 1.1% NaF (5000 ppmF) toothpaste containing Sr/F-doped bioactive glass nanoparticles (BAG or B) on demineralized irradiated dentin.

Materials and methods: Fluoride concentration and pH stability of materials upon mixing with water were assessed using a fluoride-specific electrode (n = 3) for up to 3 months. Elemental release of materials in water was determined using ICP-OES (n = 3). Fourteen extracted molars were irradiated with a cumulative dose of 70 Gy. Each tooth was sectioned into 4 specimens (n = 14/group), demineralized, and subjected to pH cycling for 14 days. Groups were treated with Prevident (PV), E5000, E5000B, and deionized water twice daily. Remineralization was assessed using ATR-FTIR (mineral-to-collagen ratio) (n = 14). Mineral precipitation was additionally examined with SEM-EDX. The in vitro cytotoxicity of the materials on L929 mouse fibrosarcoma was evaluated with the MTT test (n = 3). Kruskal-Wallis test, followed by Dunn's procedure, was used to compare the data between groups.

Result: PV demonstrated greater pH and fluoride release stability than the experimental materials. E5000B exhibited a slight reduction of fluoride release (p < 0.01, R²=0.656) and an increase in pH with time (p = 0.006, R²=0.233). The highest increase in mineral-to-collagen ratio at 14 days was detected with PV (p < 0.05). E5000B also showed a significantly higher ratio than E5000 (p = 0.014). SEM-EDX detected mineral precipitation on dentin treated with PV and E5000B but not in E5000 and DI. The cell viability of PV (56%) was significantly lower than that of E5000 (94%) and E5000B (89%) (p < 0.05).

Conclusion: The use of 5000 ppm fluoride toothpaste enhanced the remineralization of irradiated demineralized dentin, highlighting a potentially valuable strategy for preventing radiation caries. Adding bioactive glass further promoted remineralization but may require formulation adjustments to maintain toothpaste stability for clinical use.