Purpose: To estimate the incidence of traumatic dental injuries (TDI) and determining risk factors in adolescents in Luzerna, Brazil, over a period of three years. Materials and Methods: A longitudinal study was carried out with adolescents born in 1988 and 1989 attending the schools of the city. Two examinations were performed in the adolescents in the year 2001 and 2004. The sample size was 176 individuals; however, it was decided to invite all 246 students enrolled in 2001. Clinical examinations were carried out through criteria for TDI used in the National Survey, UK, in 1994. Results: The incidence ratio was of 13.2% (CI 95% 7.9-18.5). The incidence among males was 15.1% (CI 95% 7.6-22.6) and among females 11.0% (CI 95% 3.9-18.1) (p = 0.440) with a relative risk (RR) of 1.38 (CI 95% 0.60-3.14). In relation to increased incisal overjet, the incidence ratio in the exposed individuals was found to be 21.2% (CI 95% 7.3-35.1) and in the nonexposed 11.1% (CI 95% 5.7-16.8) (p = 0.122). Individuals exposed to an increased incisal overjet presented an RR of 1.91 (CI 95% 0.84-4.34). The incidence in the individuals exposed to inadequate lip coverage was 12.5% (CI 95% 2.3-22.7) and in the non-exposed it was 13.4% (CI 95% 7.4-19.5) (p = 0.879). The RR among the exposed was 0.93 (CI 95% 0.36-2.38). Conclusion: The incidence of TDI was 13.2%. For males, having increased incisal overjet and inadequate lip coverage were not considered as risks factors. Keywords: dental trauma, incidence, incisal overjet, students, trauma