Effects of fluoridated drinking water on rat enamel fluoride and its caries development
JOURNAL OF DENTAL HEALTH
The aim of the present study was to investigate the effect of fluoridated drinking water on the fluoride content of the enamel and on the development of dental caries in the rat. Twenty-one-dayold Sprague-Dawly rats were subjected to a 4-week pre-caries test period during which they were fed a non cariogenic diet and given distilled water containing 0 ppm, 10 ppm, or 50 ppm fluoride concentration as sodium fluoride. After this period, each group was fed a cariogenic diet and given distilled
... given distilled water for a further 4 weeks. The fluoride concentrations in enamel of the first or second mandibular molar after the fluoride treatment were determined weekly. The fluoride content in enamel of the molar was also determined after the end of the cariogenic period. The fissure and proximal surface carious lesions in the first and second mandibular molar were observed and scored for caries prevalence and severity following the method of Konig. The fluoride concentrations of the first molar treated with 10 ppm and with 50 ppm fluoride for 4 weeks were both significantly higher than those of the first molar treated for 1 week (P<0.05). Likewise, the fluoride contents of the second molar treated with both fluoride concentrations showed significantly higher values at 3 weeks than those at 1 week (P<0.05-0.01). The amount of fluoride uptake into the enamel of first and second molars was shown to be directly related to the level of fluoride in the drinking water with the latter being significantly higher than the former (P<0.05-0.01). The fluoride treated groups showed less caries than the control group on the sulcal surfaces of the first and second molar; especially, caries was significantly inhibited in the 50 ppm fluoride group (P<0.001). The groups receiving 10 ppm or 50 ppm fluoride developed significantly less caries than the control group on the proximal surfaces of the second molar (P<0.05). The fluoride incorporated into enamel by fluoride treatment seemed to be almost entirely retained even after the 4 week cariogenic period. The results of this study strongly suggest that enamel-bound fluorides provided prior to a cariogenic challenge conferred protection from caries, especially, from sulcal lesions.