Características radiográficas e padrões cronológicos de reabsorção apical transitória (TAB) em dentes permanentes luxados: um estudo observacional retrospectivo

Abstract

Transient apical breakdown (TAB), is a temporary phenomenon that can occur during the healing process after damage to the pulp neuro-vascular supply due to a traumatic dental injurie (TDI) or orthodontic treatment. This phenomenon was observed radiographically in the form of an expansion of the periodontal ligament space, immediately adjacent to the injured apical foramen, associated or not with internal resorption of the root canal and/or apical root resorption. This fact often leads TAB to be misdiagnosed as periapical lesions, resulting in early and unnecessary endodontic treatment. Clinically transient crown discolorations and/or loss of pulp sensibility may also occur. The etiopathogenesis of TAB and predictive factors are still unknown and clinical literature about this issue is still scarce. The present study aimed to retrospectively evaluate records 89 teeth that presented with radiographic signs of TAB after TDI, from 56 patients treated at the Dental Trauma Clinic of the Faculty of Dentistry of the Federal University of Minas Gerais during the period from 1993 to 2024. Clinical and radiographic data were collected in a dedicated Excel spreadsheet and exported to the statistical program R (version 4.0.4, Vienna, Austria, 2021). The majority of patients were male (60.3%), with a mean age at the time of trauma of 17.7 ± 6.6 years (range, 9.1 to 39.7 years). The upper central incisors were the most affected teeth (66.3%), all with complete root development and closed apex at the time of trauma (Moorrees stage 6). Extrusions (40.4%) represented the most frequent type of LTD, followed by lateral dislocations (32.6%) and subluxations (22.5%). TAB was also observed in 2 teeth with concussions and in 2 teeth neighboring alveolar process fracture. The most common TAB pattern was expansion of the PDL associated with a enlargement of the apical foramen together with resorption of the root apex, observed in 45 teeth (48.9%). Expansion of the LPD associated only with enlargement of the apical foramen was observed in 38% of the teeth and 12 teeth (13%) showed expansion of the periodontal ligament associated with resorption of the root apex. Kaplan-Meier curves demonstrated that the median time between trauma and diagnosis of TAB was 3.4 months (range, 26 days to 11.7 months) while the median time between trauma and disappearance of periapical radiolucency was 9.6 months (range from 4.8 to 34.8 months after the trauma. 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. These findings represent an important contribution for treatment decision-making during the follow-up of luxated permanent teeth as they indicate under which circumstances transient periapical radiographic changes may occur.