What is the impact of primary dental avulsion injuries on the permanent dentition?

Design Retrospective cohort study.Cohort selection Records of 2,922 patients, who attended a reference centre between 1998 and 2019 with primary dental trauma and who had radiographs and photographs, were screened to identify primary dental avulsion injuries that were followed-up until complete eruption of the permanent successors. 240 records were eligible and 194 fulfilled the inclusion criteria.Data analysis Exploratory descriptive analysis was carried out to map the occurrence and type of sequelae to the permanent tooth following primary avulsion, comparing this to the control group of permanent anterior teeth from the same children where the predecessor teeth had not suffered any type of dental trauma. Exploratory descriptive analysis was also used to link the age the primary avulsion occurred to the type of sequelae to permanent dentition. Multilevel Poisson regression analysis was performed and relative risk values and respective 95% confidence intervals were calculated to evaluate the association between avulsion and occurrence of sequelae. Confounders were included in the model to calculate their effect.Results Of the 194 patients included, there were 266 avulsed primary teeth and 115 of the permanent successors presenting with sequelae (43.2%), compared to 15.4% in the control group. Demarcated opacities were most common in both groups. Primary tooth avulsions occurring in children under two years old had a higher risk of sequelae to the permanent successor. There was also a higher risk of successor sequelae with avulsions of the lower arch compared to the upper and when three or more teeth were affected by the trauma compared to a single tooth. Avulsions in children over three years old had a lower risk of hypoplasia and those over four years old had a low risk of opacities to the successor.Conclusions Following avulsions of primary teeth, there is a higher risk of sequelae to the permanent successor in children younger than two years, where the lower jaw is involved and when multiple teeth are involved.