Prevalence of dental fluorosis and associated risk factors in Alappuzha district, Kerala.
Fluorosis is considered endemic in 15 states of India. Dental fluorosis is the most convenient biomarker of exposure to fluoride. In Kerala, although the condition is reported to be endemic in the districts of Alappuzha and Palakkad, there are no systematic epidemiological studies evaluating dental fluorosis. We studied the prevalence of dental fluorosis among school children in Ambalappuzha taluk, Alappuzha district, Kerala and evaluated the contribution of potential risk factors. We conducted a community-based, cross-sectional survey of 1142 school children (630 girls, 512 boys) in the age group of 10-17 years, using a multistage random cluster sampling technique. A pre-tested structured questionnaire was used to assess exposure to various sources of fluoride. A dental specialist examined all the children to determine the presence or absence of dental fluorosis and graded the degree of dental fluorosis using Dean's Index. The water fluoride content in the study area was obtained from the district water authority department. Bivariate associations were examined using the Chi-square and Chi-square trend tests, while multiple logistic regression was used to evaluate the association of select risk factors with the presence or absence of dental fluorosis. The overall prevalence of dental fluorosis in our study sample was 35.6% and the community fluorosis index was 0.69. The prevalence of dental fluorosis was higher in the urban compared to the rural areas (55.3% v. 16.8%; p < 0.001), and in girls compared to boys (39.2% v. 31.3%; p < 0.01). The prevalence of dental fluorosis was higher among children who consumed pipe water as compared to children who consumed well water (44.8% v. 12.7%; p < 0.001). We noted a step-wise increase in the prevalence of dental fluorosis with a corresponding increase in water fluoride content in different panchayats (p = 0.024). The principal factor associated with the presence of dental fluorosis was a high fluoride content of drinking water (OR 1.85, 95% Cl: 1.17-2.92). We did not observe any significant association between dental fluorosis and the intake of brick-tea, consumption of fish or the use of toothpaste. Dental fluorosis is a public health problem in the Ambalappuzha taluk. Active steps must be taken to partially defluoridate the water before distribution to reduce the morbidity associated with dental fluorosis in this area. Similar surveys are required in other parts of India to identify areas with high water fluoride content and determine the extent and manner in which defluoridation can be carried out.