Comparison of Fluoride Content in Drinking Water and Prevalence of Dental Fluorosis in 6 - 12-Year-Old Students in Mariwan (a Cold Region) and Behbahan (a Warm Region) during the 2013 - 2014 Educational Year

Fluoride plays an important role in preventing dental caries. Low fluoride concentrations cannot prevent dental caries, but ingestion of very high concentrations of fluoride during enamel development and maturation could lead to fluorosis. Fluoridation of drinking water is the most effective and inexpensive method for preventing caries. The mandated concentration of fluoride incorporated into drinking water should consider the mean temperature of each region. The aim of the present study was to evaluate the prevalence of fluorosis in children aged 6 - 12 in Mariwan and Behbahan and determine the fluoride content of drinking water in these two towns. In the present descriptive and cross-sectional study, 13 water samples were taken from homes in Behbahan, 1 sample from the town’s water reservoir, 10 samples from homes in Mariwan (5 samples for each reservoir) and 1 sample each from the town’s 2 reservoirs. The 26 samples (23 from homes and 3 from reservoirs) were taken in polyethylene containers. The SPANDS colorimetric technique was used to determine fluoride content. Homes that used home-based water purification systems were excluded from the study. In addition, 128 students (62 girls and 66 boys) in Behbahan and 90 students in Mariwan were randomly selected. Dean’s index was used to determine dental fluorosis. The mean yearly temperatures of the two towns were obtained from the metrological bureaus of the two towns. The means fluoride content of water in Behbahan’s reservoir and Mariwan’s reservoirs 1 and 2 were 0.7, 0.24 and 0.036 ppm, respectively. The mean fluoride content of Behbahan’s home waterlines and in the relevant home waterlines of reservoirs 1 and 2 in Mariwan were 0.67, 0.218, and 0.054 ppm, respectively. There were no significant differences between the relevant reservoirs. The prevalence of fluorosis in Behbahan was as follows: 84.4% healthy, 10.9% questionable, 1.6% very mild, 2.3% mild, and 0.8% moderate. In Mariwan, the prevalence in areas related to reservoir 1 was 96.7% healthy and 3.3% questionable; in areas related to reservoir 2 it was 94.4% healthy and 5.6% questionable. The fluoride content of drinking water in reservoirs and at homes was below the optimal level in Mariwan. No differences were observed from the standard levels in Behbahan. There were no differences in fluoride content of water in reservoirs and in home pipelines, indicating no tangible changes in fluoride content from the reservoirs to the homes. In neither of the towns was severe fluorosis observed. There was no significant difference in the prevalence and severity of fluorosis between genders.