Effect of different protocols in preventing demineralization in irradiated human enamel, in vitro study.

Background: This in vitro study evaluated the efficacy of professional and home-use fluoride regimens for protecting irradiated enamel, undergoing pH cycling resembling xerostomia.

Methods: Sixty human premolar teeth were irradiated with a total dose of 70 Gy and subsequently sectioned into 3 × 3 cm enamel slabs. These slabs were randomly distributed into five groups (n = 12 per group): professional-use groups received fluoride varnish either weekly (FV1) or biweekly (FV2); home-use groups applied 5000 ppm (FT5) or 1450 ppm (FT) fluoride toothpaste; and a control group (control) received no treatment. Following radiation, microhardness was measured to establish baseline values. Following 28 days of pH cycling and concurrent fluoride therapy, microhardness was reassessed on day 7, 14, 21, and 28. After the pH cycling period, surface morphology was examined using scanning electron microscopy.

Results: All groups demonstrated declines over the 28-day pH cycling period. FV1 and FV2 maintained higher microhardness relative to control (p < 0.0001). FT5 consistently showed better preservation of enamel microhardness compared to FT (p < 0.0001), with both outperforming control (p < 0.0001), albeit FT to a lesser extent.

Conclusion: Fluoride treatments significantly enhanced the enamel's resistance to pH reduction caused by radiation. It is recommended to apply professional fluoride varnish biweekly and use 5000 ppm fluoride toothpaste twice daily for the most effective enhancement of pH resistance in irradiated enamel.