Purpose: This laboratory study aimed to determine whether laser activated fluoride (LAF) therapy of sensitive dentine causes conversion of apatite mineral to fluorapatite (photonic conversion) and thereby reduces the risk of dental erosion. Materials and Methods: X-ray photoelectron spectroscopy was used to quantify changes in the atomic concentration of the elements fluorine, calcium, oxygen, phosphorus, carbon, nitrogen, and silicon, at five depths up to 52 nm in human dentine slabs with patent dentine tubules, which were either treated with neutral sodium fluoride gel (12,300 ppm) only, untreated, or subjected to laser-activated fluorid therapy (LAF) over a 12-week period. Results: Fluorine to calcium ratios were increased from zero (control) to 0.27 and 0.28 after fluoride gel and LAF, respectively. However, the chemical composition of dentine was affected by LAF, with the altered fluorine binding energy of 684.6 eV corresponding to formation of fluorapatite. No conversion to fluorapatite occurred when fluoride gel was applied under identical conditions but without lasing. Conclusion: Partial conversion of apatite minerals with LAF would contribute to the documented protective effects of LAF against dental erosion, and explains the benefits gained clinically when this treatment is applied to sensitive cervical root surfaces.
Keywords: apatite, fluoride, transformation, erosion, dentine