Incidence of dental trauma among adolescents: a prospective cohort study.

We estimated the incidence of traumatic dental injuries (TDI) in a 2-year follow-up of adolescents with and without previous dental trauma and verified the hypothesis that individuals with previous trauma are more prone to recurrent TDI events. The present study was developed in three phases. First, a dental trauma cross-sectional study was carried out with 2260 schoolchildren aged 11-13 years in Biguaçu, southern Brazil. In the second phase, a case-control study was developed to identify risk factors associated with dental trauma. The third step was a 2-year longitudinal observational study with the participants of the second phase of the study. The exposed group of individuals with previous dental traumatism (208) and a non-exposed group (208) of participants who had no previous signs of dental trauma were followed up for 2 years. Descriptive, univariate, simple and conditional multiple logistic regression analyses were performed. The greatest incidence of dental trauma was identified among adolescents with previous dental trauma (11.9%-11.44/1000 incisors) when compared with those without previous dental trauma (2.7%-2.45/1000 incisors) (P < 0.001). In the study period, adolescents with previous dental trauma showed a 4.85 times greater odds ratio for presenting further dental trauma when compared with adolescents without previous dental trauma (P = 0,005) after adjusting for incisal overjet, lip coverage and mother's schooling. A notable difference was observed regarding the incidence of TDI between the case and control groups. Individuals with previous dental trauma had greater chances of developing develop further dental trauma in a 2-year follow-up.