The objective of this study was to assess the prevalence, aetiology, place of occurrence and rates of treatment of traumatic dental injuries (TDI) among 12-year-old schoolchildren in Herval D'Oeste, Brazil. A cross-sectional survey was carried out through clinical examination of upper and lower permanent incisors and interviews with 297, 12-year-old schoolchildren enrolled in public and private schools. Intra-examiner diagnosis variability, measured by kappa values on tooth-by-tooth basis was above 0.7. The prevalence of TDI was 17.3% (95% CI 12.7–21.9). Children who had an incisal overjet size >5 mm were 3.5 (95% CI 1.5–8.1) times more likely to have TDI than children who had an incisal overjet of <5 mm (P = 0.005). The most common type of injury found was enamel fracture alone. Of the total of 87 traumatized teeth, only 27.6% were treated. Acid etch restorations were the most common treatment provided. Acid etch restorations were the most common type of treatment needed. The majority of the cases of TDI occurred at home (17.8%) and at school (17.8%). Collisions (24.5%), mainly with doors, and physical leisure activities (20.0%) such as cycling and playing soccer were the main activities related to TDI aetiology. It can be concluded that there is a great treatment need reflecting neglect of TDI treatment. The main causes of TDI were collisions and physical leisure activities.