A study on reduction in the rate of progress and prevention of the root caries by fluoride-releasing polymers

Periodontal disease and aging often expose the relatively caries-prone root dentin.This study investigates the effect of light-cured fluoride-releasing sealant(F-sealant)containing methacryloyl fluoride(MF)-methyl mathacrylate(MMA)copolymer on the anti-caries properties of the root dentin；e.g.，acid resistance and abrasion resistance.F-sealant and abrasion resistance greater than that of root dentin。Following application of F-sealant，the root dentin acquired a scanning electron microscopically demonstrable sealant penetration layer of about3&lt；micrn&gt；m in thickness。The rate of fluoride release from F-sealant into a phosphate buffer(pH7，37℃)was about12-30&lt；micrn&gt；g/day during the first 24hr，rapidly decreased by the 100th day and thereafter maintained a constant value of about1-2&lt；micrn&gt；g/day until the 300th day.At the end of experiment(The 540th Day)，the F-sealant still continued releasing a small amount of fluoride(0.5-1&lt；micrn&gt；g/day)。The greater the molar fraction of MF，the greater the rate of fluoride release was。Immediately after the F-sealant application，fluoride was detected at the depth of10&lt；micrn&gt；m from the dentin surface。During the incubation of preparations in a phosphate buffer(pH7，37°C)，fluoride gradually infiltrated the dentin and reached100&lt；micrn&gt；m at the 90th day.The acid resistance of the dentin after removal of F-sealant was significantly greater than that after removal of C-sealant(without MF-MMA copolymer)。This acid resistance gradually increased for up to 90days after application of F-sealant.The above results suggest that the F-sealant enhances the acid resistance of the dentin through a long term transmittal from the F-sealant to the dentin of fluoride。This enhancement of acid resistance of the dentin，together with a possible contact inhibition of the dentin from the oral environment，is considered to contribute to reduction of the rate of progress of and/or prevention of the root caries。

Periodontal disease and aging often expose the relatively caries-prone root dentin. This study investigates the effect of light-cured fluoride-releasing sealant (F-sealant) containing methacryloyl fluoride (MF) - methyl mathacrylate (MMA) copolymer on the anti-caries properties of the root dentin; e.g., acid resistance and abrasion resistance.F-sealant and abrasion resistance greater than that of root dentin. Following application of F-sealant, the root dentin acquired a scanning electron microscopically demonstrable sealant penetration layer of about 3 <micrn>m in thickness. The rate of fluoride release from F-sealant into a phosphate buffer (pH 7, 37゜C) was about 12-30 <micrn>g/day during the first 24 hr, rapidly decreased by the 100th day and thereafter maintained a constant value of about 1-2 <micrn>g/day until the 300th day. At the end of experiment (the 540th day), the F-sealant still continued releasing a small amount of fluoride (0.5-1 <micrn>g/day). The greater the molar fraction of MF, the greater the rate of fluoride release was. Immediately after the F-sealant application, fluoride was detected at the depth of 10 <micrn>m from the dentin surface. During the incubation of preparations in a phosphate buffer (pH 7, 37゜C), fluoride gradually infiltrated the dentin and reached 100 <micrn>m at the 90th day. The acid resistance of the dentin after removal of F-sealant was significantly greater than that after removal of C-sealant (without MF-MMA copolymer). This acid resistance gradually increased for up to 90 days after application of F-sealant.The above results suggest that the F-sealant enhances the acid resistance of the dentin through a long term transmittal from the F-sealant to the dentin of fluoride. This enhancement of acid resistance of the dentin, together with a possible contact inhibition of the dentin from the oral environment, is considered to contribute to reduction of the rate of progress of and/or prevention of the root caries.