Aim: To determine the prevalence, severity, and intraoral distribution of dental fluorosis among 15-year-old school children in Kurunegala district of the North-Western Province, Sri Lanka.

Method: A cross-sectional study was conducted among 15-year-old school children residing in Kurunegala district since birth. One thousand and forty participants from 42 schools were selected using two stage cluster sampling method. A single calibrated dentist examined all participants for dental fluorosis using Thylstrup and Ferjeskov index. Water samples from the drinking water source of participants were analyzed for their fluoride content.

Results: The prevalence of dental fluorosis was 52% and 42% when TF score ? 0 and TF score ?1 were considered as cut-offs for dental fluorosis respectively. Of those with dental fluorosis, a majority (20.9%) had a TF score of 2. Only 0.5% had a TF score of 6 which was the highest score observed for any participant. With regards to the intra-oral distribution of dental fluorosis, the premolars were the most affected teeth and the least affected were the central incisors. The fluoride levels in the drinking water source ranged between 0.0-1.9 mg/L and the prevalence of dental fluorosis increased with the increase in the fluoride level in drinking water source.

Conclusions: The prevalence of dental fluorosis was high and it increased with the increase in the fluoride content in the drinking water source.