Effect of Fluoride-releasing Resin Fissure Sealant on the Decalcification Layer of Root Dentin

本研究的目的是评价释氟封闭剂对龋病的预防作用及对龋病进展的影响。该密封剂含有甲基丙烯酰氟和甲基丙烯酸甲酯的共聚物，通过水解反应释放氟离子（F-密封剂）。不具有氟化物释放共聚物的密封剂（C-密封剂）也被估计为对照。牙本质块是从离体牛牙齿的根部切下的。在牙本质表面上施加密封剂后，将样本储存在去离子水中7天。在机械去除密封剂后，将样品浸入乙酸缓冲溶液（pH 4.0）中40小时。同时研究了在脱钙前牙本质上应用释放氟化物的封闭剂是否能防止龋样病变的进展。通过将样品浸入pH 4.0的乙酸缓冲溶液中12小时来进行预脱钙。在施加密封剂的情况下，将样品在去离子水中储存7天。去除密封剂后，对样本进行后脱钙（pH 4.0乙酸缓冲液，40小时）。通过测量显微X线片上的硬度和吸收的病变深度来评估封闭剂的抑制作用。对于完好牙本质，损伤深度的顺序为F封闭剂组<C封闭剂组<未处理组。对于脱钙前的牙本质，F封闭剂和C封闭剂的损伤深度基本相同，但比未处理的牙本质明显变窄。显微硬度测试结果显示，F封闭剂处理后的牙本质损伤区比C封闭剂处理后的牙本质损伤区硬。结果表明，应用释氟封闭剂能抑制暴露根面龋的发生和发展。

The purpose of this study was to estimate the effect of the fluoride-releasing sealant on the prevention from caries and fathermore progressing. The sealant contains the copolymer of methacryloyl fluoride and methylmethacrylate which releases fluoride ion by hydrolytic reaction (F-sealant). The sealant with no fluoride-releasing copolymer (C-sealant) was also estimated as a control. The dentin blocks were cut from the root parts of extracted bovine teeth. The specimens were stored in deionized water for 7 days after application of the sealant onto dentin surface. After removing the sealant mechanically, the specimen was immersed in acetic buffer solution (pH4.0) for 40 hours. It was also investigated whether fluoride-releasing sealant applied onto pre-decalcified dentin prevents the progress of caries-like lesion. Pre-decalicification was produced by immersion of specimen in pH4.0 acetic buffer solution for 12 hours. The specimen was stored in deionized water for 7 days with the application of the sealant. After removing the sealant the specimen was subjected to post-decalcification ( pH4.0 acetic buffer solution, 40 hours). Inhibitory effect of the sealant was estimated by the measurement of hardness and the depth of lesions absorbed in microradiograph. For the sound dentin, the order of the depth of lesion was F-sealant group < C-sealant group < no treatment group. For the pre-decalcified dentin, although the depth of lesion was almost same between F-sealant and C-sealant, they were significantly narrower than that without any treatment. The microhardness testing showed that the lesion of dentin treated with F-sealant was harder than that with C-sealant. The results suggested that the application of fluoride releasing sealant inhibited the production and progress of caries on exposed root surface.