High prevalence of dental fluorosis among schoolchildren in three villages in Vavuniya District: an observational study

Studies of groundwater sources in Sri Lanka show that in the entire Northern, North Central, Uva and Eastern Provinces, and also in a large area of the North Western Province, groundwater fluoride content is within the range 1.0 mg/l and 3.0 mg/l. The WHO recommended safe upper limit of fluoride for drinking water is 1.5 mg/l. Our objective was to determine the prevalence and degree of dental fluorosis in a cohort of schoolchildren in Sinnasippikulam in Vavuniya District, the fluoride content in their serum and urine, and fluoride levels in drinking water in dug wells of the area. Invitations in Tamil and Sinhala were sent to all households by courier. Demographic information and oral hygiene practices of 307 responsive children were recorded by interviewing children and their mothers. Detailed clinical examinations were performed according to WHO basic methods, with some modifications. Assessment of dental fluorosis in the children was done according to Dean’s Index codes and criteria. We found drinking water sources (dug wells) in Sinnasippikulam (n= 82) to have a high mean concentration of fluoride ( x̄ 1.58+ 0.69 mg/l). Of 307 children examined, 224 (72.9%) had clinical evidence of dental fluorosis of varying degrees of severity. The mean fluoride level in serum of schoolchildren was 0.198 mg/l (SD + 0.074; S.E.M. 0.013), and in their urine, 1.44 mg/l (SD + 0.59; SEM 0.11). Our results show that harmful levels of fluoride are extremely common in groundwater sources in the study area, and consequently, dental fluorosis is highly endemic (72.9%) among resident schoolchildren.