This study reports on the etiology and environment where dental injuries occurred and assesses the relationship between dental trauma, socio-economic status and dental caries experience. A population-based, matched case-comparison study was undertaken in 30 schools in two Ontario communities. Dental hygienists calibrated in the use of the Dental Trauma Index (DTI) screened 2422 children aged 12 and 14 years using DTI and Decayed, Missing and Filled Teeth indices. Cases (n = 135) were children with evidence of dental injury. Controls (n = 135) were children randomly selected after screening and matched with cases according to age and gender. Questionnaires were mailed to parents and children. Prevalence of dental injury was 11.4%, mostly minor injuries 63.7% (enamel fracture not involving dentin), affecting one upper central incisor (70.4%). The mean age at the time of dental injuries was 9.5 years (SD = 1.49; range: 6–13 years). Dental trauma most often occurred among boys at school because of falls or while playing sports. The relationship between dental injuries and the socio-economic indicators chosen was not statistically significant. However, a statistically significant direct relationship (P < 0.001) was shown between increased caries experience and dental injuries. This should focus attention on possible common-risk factors such as health-related behavioral problems that may affect both dental disease and dental injuries.