Introduction. The optimum amount of fluoride in drinking water has been determined 1ppm for special areas by WHO. In jarghoyeh the amount of fluoride in drinking water is less than optimum, but dental fluorosis has been observed in a great deal. The purpose of this comparative study is to determine the prevalence of dental fluorosis and the mean DMFT values and their relationship among guidance school students in Jarghoyeh Olya and Jarghoyeh Sofia.
Methods. The main reason of this research was to compare fluorosis prevalence in Jarghoyeh Sofia and Jarghoyeh Olya. A pilot study was carried out and 191 person for the number of specimen was determined. Since DMFT was also to be investigated, the number of specimen was incresed., Finally 256 guaidance school students in Jarghoyeh Sofia and 263 students in Jarghoyeh Olya were selected by sharing method. The DMFT and TF indices, respectively, were used to asses dental caries and dental fluorosis.
Results. The prevalence of dental fluorosis in Jarghoyeh Olya was 65.8 percent and in Jarghoyeh Sofia was 44.9 percent. The mean DMFT indices in these two regions were 2.2471 and 2.0508 respectively. Evaluation of amounts of DMFT in different scores of TF index, shows that from zero score to 1 score, DMFT decreases. Then it gradually increases and as a result in 5≤ score it reaches to the highest level.
Discussion. Factors such as hot climate and salty drinking water causes the inhabitants to drink more water. Also they drink tea a lot. Thus in spite of the low fluoride content of drinking water, prevalence of dental fluorosis was high. During tooth mineralization, fluoride reacts with hydroxyapatite crystals and produces fluorohydroxyapatite, resulting in higher resistance to tooth caries. On the other hand, absorption of excessive fluoride, results in disorder of formation of enamel. This leads to a hypoplastic and porose enamal. This enamel has lower resistance to caries and higher potential to absorb dental plaque. Maybe this is the reason of decreasing the caries prevalence in low degrees of fluorosis and increasing of caries prevalence in high degrees of fluorosis in this research.


Fluorosis, Fluoride, Decayed, Missing, Filling