Purpose: To assess the prevalence of dental trauma (DT) and its associated factors in 9- to 14-year-olds. Subjects and Methods: A cross-sectional survey was carried out through clinical examination of the permanent incisors and canines of 907 schoolchildren (9 to 14 years old, average age = 11 ± 0.5 [SD] years, 55% female and 45% male) enrolled in 20 public schools in Isfahan, Iran. The demographic data, history and cause of trauma were recorded during patient interviews and with a structured questionnaire filled in by their parents. The overjet, lip coverage, and visible signs of DT (permanent incisors only, similar to the classification used by the US National Health and Nutrition Examination Survey 1988-1994, NHANES III) were recorded. DT in permanent canines were also recorded. Results: Approximately 36% (n = 325) recalled the occurrence of dental trauma, but only 23.8% (n = 216) of children had visible signs of dental trauma to the permanent incisors (girls [18.8%], boys [29.9%], OR = 0.54; 95% CI 0.40- 0.74; p = 0.000). The maxillary central incisors were commonly injured (69.5%). The most frequent types of injuries were the enamel fracture (59.0%), craze lines (16.3%), and enamel and dentin fracture (13.4%). Tooth avulsion was seen in 0.7%. No significant association was found between dental trauma and increased overjet of > 3 mm (p = 0.328), but a tendency was identified for overjet > 5 mm (OR = 1.51; 95% CI 0.89-2.58; p = 0.060). The relationship between DT and lip coverage was statistically significant (OR = 1.63; 95% CI 1.18-2.25; p = 0.003). Violence (30%) and fall (22.7%) were the main causes of DT. Conclusion: The prevalence of DT in permanent incisors was high (23.8%) and significantly lower in girls. The association between DT and lip coverage was significant. There was no association between DT and increased overjet of > 3 mm. Keywords: dental trauma, lip competence, oral epidemiology, overjet, permanent incisors