Objectives:The purpose of this retrospective cohort study was to investigate the occurrence of sequelae in the permanent teeth after avulsion of their primary antecessors and to evaluate the factors associated with this occurrence. Methods:We screened 2922 records of patients with photographic and radiographic images who attended a reference centre for dental trauma in the primary teeth from 1998 to 2019. Among them, 240 were eligible records of children who had suffered avulsion of the primary incisors and were followed up until complete eruption of the permanent successors. Multilevel Poisson regression analyses were conducted between the explanatory variables related to children and avulsed teeth; outcome variables were occurrences of any type of sequelae in the permanent teeth, opacities, hypoplasia and malformation. Relative risks (RRs) and respective 95% confidence intervals (95% CIs) were calculated.Results: Among the 240 children's records, 194 fulfilled the inclusion criteria. Finally, we found 266 primary avulsed teeth and 115 (43.2%) permanent teeth presenting with sequelae. Avulsion occurring when children were older than 4 years (RR = 0.48; 95% CI = 0.24-0.95) had lower risks for developing sequelae than children aged 0-2 years of age. Additionally, when avulsion occurred in the lower dental arch (RR = 1.45; 95% CI = 1.06-1.99) and when three or more teeth were affected (RR = 1.57; 95% CI = 1.02-2.41), the occurrence of sequelae in the permanent teeth was more probable than if avulsion occurred in the upper arch and affected only a single tooth. Age older than 3 years was a protective factor for the occurrence of hypoplasia and age older than 4 years protective for the occurrence of opacities. Conclusions:The risk of sequelae in the permanent teeth after avulsion of their antecessor is higher when the trauma occurs in young children (<2 years) and in patients with avulsions of greater magnitude, such as when it affects the lower jaw, and more teeth are involved.

BackgroundPrimary lower incisors are susceptible to traumatic dental injury (TDI), which may affect both primary and permanent dentitions.AimThis 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.DesignDental 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.ResultsOne 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.ConclusionsThe 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.