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

1987 Fiscal Year Final Research Report Summary

• Project/Area Number: 61480397
• Research Category: Grant-in-Aid for General Scientific Research (B)
• Allocation Type: Single-year Grants
• Research Field: Conservative dentistry
• Research Institution: Osaka University
• Principal Investigator: TSUCHITANI Yasuhiko Osaka University Professor, 歯学部, 教授 (40028709)
• Co-Investigator(Kenkyū-buntansha): KAWABE Tsuyoshi Osaka University Instructor, 歯学部, 助手 (80177732) ; IGA Miki Osaka University Instructor, 歯学部, 助手 (90176066) ; SHIBATANI Takako Osaka University Instructor, 歯学部, 助手 (10127235)
• Project Period (FY): 1986 – 1987
• Keywords: Prevention of root caries / fluoride-releasing polymer / fluoride uptake / acid resistance / 耐摩耗性

Research Abstract

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.