DENTAL FLUOROSIS IN CHILEAN CHILDREN - EVALUATION OF RISK-FACTORS

The purpose of this case-control study was to determine the associatio n between very-mild-to-moderate enamel fluorosis and exposure during e arly childhood to fluoridated water, mainly through ingestion of powde red milk. Analysis was performed on 136 residents of the optimally flu oridated community of San Felipe in the Chilean Fifth Region, who were categorised into one of three groups according to their age when wate r fluoridation was introduced in 1986: Group I was born after 1986; Gr oup II was 16-24 months old in 1986; and Group III was >24 months of a ge. The case and control subjects were selected on the basis of a clin ical examination given in July 1996. Dean's scoring system was used to determine fluorosis status. Risk factor exposure was ascertained by a questionnaire used in interviews with mothers of participating childr en. Logistic regression analysis, after adjustment for confounding var iables, revealed that very-mild-to-moderate enamel fluorosis of perman ent central maxillary incisors (CMI) was strongly associated both with the age of the subjects when water fluoridation began and with breast -feeding duration for children belonging to Group I. Subjects in Group I were 20.44 times more likely (95% CI: 5.00-93.48) to develop CMI fl uorosis than children who were older than 24 months (Group III) when f luoridation began. Subjects who were between 16 and 24 months old when water fluoridation began were 4.15 times more likely (95% CI: 1.05-16 .43) to have CMI fluorosis than children older than 24 months. An inve rse association was found with breastfeeding duration (OR=0.86, 95% CI : 0.75-0.98) among Group I subjects but not in Groups II and III. Resu lts obtained suggest that the current fluoride concentration in drinki ng water may be contributing to fluorosis. Further studies will be nec essary to determine the relative competing risks of dental fluorosis a nd dental caries in Chilean children in order to establish the most ap propriate water fluoridation level in Chile.