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Fluoride (F) distribution in human teeth was measured using an in-air micro-PIGE and micro-PIXE system. Class V cavities in the extracted teeth were prepared with Fluoro-Bond Shake One to provide a thin layer of an F-releasing material (FRM). The cavities were then filled with Beautifil Flow F10 (FRM, Group I) or LITE FIL IIP (non-FRM, Group II). Following a four-year period, specimens were cut longitudinally perpendicular to the cavity floor. The F distribution was measured at the floor of the cut surface. The position including 90% of the intact Ca level was defined as the wall surface. Based on this demarcation, indices of F distribution (surface F concentration and F penetration depth) were determined. Thickness of FRM thin layers varied (≈339 μm) and did not affect F distribution. Both values of F distribution indices in Group I [821-8763 (mean 3797) ppm, 34-668 (mean 241) μm] were significantly larger than those in Group II [0-7064 (mean 1865) ppm, 0-143 (mean 21) μm]. The F distribution in Group I was affected more by the filling material than by the FRM thin layer during the four-year exposure. Methodologies using this system may give insightful information for the development of new dental materials. [ABSTRACT FROM AUTHOR]

Whether fluorine penetrated from material completely incorporates into tooth mineral is a matter of debate, although it is well known that the fluoride from material penetrates directly into tooth structures. The purpose of this study is to determine tooth-bound fluoride uptake from fluoride-containing materials using PIGE/PIXE system at the Wakasa Wan Energy Research Center. Class V cavities in buccal surfaces of eighteen extracted human teeth were drilled and filled with six fluoride-containing materials. After being stored in distilled water for one year, a longitudinal section including materials was obtained from each tooth. Fluorine and calcium distribution of specimens were evaluated using PIGE/PIXE system. After evaluation, the specimens were immersed in 10 mL of 1M KOH solution and were agitated at room temperature for 24 h to remove a KOH soluble fluoride. The specimens were washed with 200 mL distilled water and left to dry. Again, to estimate tooth-bound fluorine (KOH-insoluble fluoride) uptake, the same portion of the specimens after KOH treatment were evaluated using PIGE/PIXE system. It was confirmed that fluorine penetrated from material partly incorporated into tooth mineral. This tooth-bound fluoride have the potential to prevent dental caries after loss of the bond between the filling material and tooth structure. [ABSTRACT FROM AUTHOR]