Abstract
In a technical report of the WHO, it is described that fluoride mouth-rinsing is contraindicated or not recommended for children below the age of 6 years, as it might contribute to the risk of dental fluorosis. However, no epidemiologic evidence has shown that the fluoride mouth-rinsing is a risk factor for increasing dental fluorosis in children in communities where fluoride was in short supply such as Japan. To determine the prevalence of dental fluorosis, an epidemiologic investigation was conducted in a part of the regular school dental health examination in the spring of 1997, among Japanese 5 th and 6 th grade elementary schoolchildren in three communities of different experience of fluoride. The children: (1) participated in a fluoride mouth-rinsing program since 4 years of age (5 times/week rinsing with 0.05% sodium fluoride solution, in preschool and weekly rinsing with 0.2% sodium fluoride solution in elementary school) in fluoride-deficient communities (FMR group); (2) resided in an area with naturally fluoridated water (about 0.8 mg F/l) for their entire life without a fluoride mouth-rinsing program (Nat. F group); and (3) had no exposure to fluoride (Control group). The Fluorosis Risk Index proposed by Pendrys was modified and applied to detect individual enamel opacity on 7 numbers in all of the developmental age-related enamel surface zones, which were formed between the second and sixth birthday, designated as classification II in three restricted teeth, the upper right first premolar and central incisor and lower right first premolar. If either more than two questionable findings or any number of positive findings in classification II were found in a child, then he/she was classified as having dental fluorosis (fluorosed enamel opacity). If a child had any enamel opacity that was not induced by fluoride, then he/she was classified as having non-fluorosed enamel opacity. One dentist screened enamel opacity in 268 children. Cohen's Kappa value of reproducibility in diagnosis of enamel opacity was 0.84. If any of the restricted teeth of the child were unerupted or he/she had disturbance of diagnosis, for example, orthodontic therapy, he/she was excluded from analysis. Ultimately, 222 children were included in the present analysis. The prevalence of fluorosed enamel opacity in Classification II of the FMR group was less than that of the Control group (Odds ratio; 0.358, 95%CI; 0.127-1.008), which was not statistically significant. The prevalence of fluorosed enamel opacity in Classification II of the Nat. F. group was significantly larger than that of the Control group (Odds ratio; 3.112, 95%CI; 1.515-6.395). The prevalence of non-fluorosed opacity in both the FMR group and the Nat. F. group was lower than that in the Control group, but it was not statistically significant. From the results of this study, a fluoride mouth-rinsing program from preschool (4 years of age) was not indicated to be a risk factor of dental fluorosis in fluoride-deficient communities.
