Despite contributing to a reduction in dental caries, improper use of fluoridated toothpaste could add to the burden of dental fluorosis in children. To assess the association between tooth-brushing practices such as the type and amount of toothpaste used, frequency of tooth brushing, parental assistance in tooth brushing, timing of tooth brushing and dental fluorosis in school children in Kurunegala district, an endemic area for dental fluorosis in Sri Lanka. For this case-control study, a sex-matched sample of 15-year-old school children attending government schools in Kurunegala district and who were lifetime residents of the district was selected. Dental fluorosis was measured using the Thylstrup and Ferjeskov (TF) Index. Those children with a TF⟩1 were considered as cases and those with a TF score of 0 or 1 served as controls. An interview of parents/caregivers of the participants was used to assess risk factors for dental fluorosis. The fluoride concentration in drinking water was measured using spectrophotometry. Data analysis used chi-square tests and conditional logistic regression. Tooth brushing ≥ twice/day, brushing after breakfast and parent/care giver brushing the child's teeth reduced the likelihood of developing fluorosis. Use of fluoridated toothpaste adhering to the recommended guidelines could prevent dental fluorosis in children in this endemic area.