Radiographic characteristics and chronological patterns of transient apical breakdown (TAB) in luxated permanent teeth: A retrospective observational study.

Aim: To describe radiographic features, clinical signs and symptoms, and chronological patterns of post-traumatic transient apical breakdown (TAB) in luxated permanent teeth.

Methodology: Records from 56 patients treated at the Dental Trauma Clinic of the School of Dentistry of the Federal University of Minas Gerais from 1993 to 2024 were accessed to collect demographic, clinical, and imaging features of 89 teeth that presented with radiographic signs of TAB after traumatic dental injury (TDI). Kaplan-Meier curves were built to illustrate the time elapsed between trauma until TAB onset and resolution for the whole sample and for each one of the TAB patterns. A Cox regression was used to explore the effect of clinical covariates in both events.

Results: Patients' mean age at the time of trauma was 17.7 ± 6.6 years (range 9.1 to 39.7 years), with most being male (59.6%). All included teeth were mature at the time of trauma (Moorrees stage 6). Upper central incisors (66.3%) were predominant and mostly suffered extrusions (40.4%) or lateral luxations (32.6%). TAB was observed as an expansion of the periodontal ligament associated with a "V-shaped" widening of the apical foramen together with apical root resorption in 45 teeth (50.6%). Expansion of the periodontal ligament associated with "V-shaped widening of the apical foramen only was observed in 32 teeth (36%), and 12 teeth (13.5%) showed expansion of the periodontal ligament associated with apical root resorption only. The overall median time for TAB onset was 3.2 months (range, 26 days to 8 months), being significantly lower for pattern 2 (1.8 months) when compared to TAB pattern 1 and 3 (3.4, and 3.9 months) respectively (Logrank test p values < 0.001 for both comparisons). The overall median time for TAB regression was 9.1 months (range, 4.8 to 34.8 months) after trauma. Again, TAB pattern 2 presented lower periods when compared to TAB pattern 1 and 3 (Logrank test p values < 0.001 and 0.013, respectively). Color changes were not frequent neither at the time of TAB onset nor at the time of TAB resolution. However, while most teeth (53.3%) did not respond to pulp sensibility tests at the time of TAB onset, this proportion decreased to 17.6% by the time of TAB resolution.

Conclusion: TAB was mainly diagnosed within four months after luxation of mature teeth, most of them being resolved within the 1-year of follow-up. The most frequent TAB pattern was an expansion of the PDL associated with a "V-shaped" widening of the apical foramen together with external apical root resorption.

Clinical relevance: These findings represent an important contribution for treatment decision-making during the follow-up of luxated permanent teeth.