Traumatic dental injuries in the primary lower incisors.

Background: Primary lower incisors are susceptible to traumatic dental injury (TDI), which may affect both primary and permanent dentitions.

Aim: This study aimed to evaluate the prevalence of TDIs in the primary lower incisors and the factors associated with their occurrence and with the incidence of sequelae in the permanent successor teeth.

Design: Dental files (n = 2926) from patients who attended a reference center for dental trauma in the primary teeth, from 1998 to 2020, were screened. Multilevel Poisson regression analyses were conducted between exploratory variables related to the traumatized teeth and outcome variables: occurrences of severe TDI and sequelae in the permanent successor. Prevalence ratios (PRs), relative risks (RRs), and respective 95% confidence intervals (95% CIs) were calculated.

Results: One hundred and thirteen (3.9%) children and 208 teeth presented with TDIs in the primary lower incisors. The prevalence of severe TDI was lower in 4-year-olds (PR = 0.43; 95% CI = 0.19-0.94) than in 2-year-olds. Moreover, severe TDI was significantly associated with the occurrence of sequelae in the permanent successors (RR = 3.97; 95% CI = 1.72-9.18), when compared to not severe TDI.

Conclusions: The prevalence of TDI in the primary lower incisors is low, with a higher prevalence in children younger than 3 years. Older children also present less frequently with severe TDI, and the risk of sequelae in permanent teeth is higher following severe TDI.