Objective: To describe the caries lesion transition pattern in permanent tooth surfaces over 2 years among a convenience sample of children in a fluoridated (0.8 ppm F) low-socioeconomic community of Brazil. Material and methods: One hundred forty-nine schoolchildren (7–12 years) were examined for caries using Nyvad criteria at baseline and after 2 years. Descriptive analysis was used to evaluate caries lesion transition patterns. Results: Less than 1% of sound surfaces and non-cavitated caries lesions at baseline progressed to cavitation stage within 2 years. 12.7% of the active non-cavitated (ANC) lesions became inactive, 34.7% regressed to sound, 48.0% remained active, and 4.6% progressed to cavitated/filled stages at follow-up. Similarly, 55.2% of the inactive non-cavitated (INC) lesions at baseline remained inactive, 33.3% regressed to sound, 8.0% progressed to cavitated/filled lesions, while only 3.5% progressed to ANC lesions. Conclusion: The caries lesion transition pattern in this child population exposed to water fluoride and fluoride toothpaste showed that a low proportion of sound surfaces and non-cavitated lesions progressed to cavitation within the 2-year follow-up. Caries arrest was mainly ascribed to a high proportion of active non-cavitated lesions regressing to sound or inactive lesions. Clinical relevance: Caries activity can be controlled by regular exposure to fluoridated water and fluoridated toothpaste.