External Apical Root Resorption in Vital and Endodontically Treated Teeth Following Fixed Orthodontic Treatment: A Retrospective Longitudinal Panoramic Study

<b>Objective</b>: External apical root resorption is a frequent complication of orthodontic treatment, and the response of endodontically treated teeth remains controversial. This study aimed to compare external apical root resorption (EARR) in endodontically treated teeth and vital teeth following fixed orthodontic treatment in patients with Angle Class I, II, and III malocclusions using digital panoramic radiography. <b>Methods</b>: This retrospective longitudinal study included 60 patients (mean age: 16.3 ± 2.4 years) who underwent non-extraction fixed orthodontic treatment. A paired contralateral within-subject design was used, whereby each patient contributed one endodontically treated tooth and its symmetrical untreated vital counterpart. Root length was measured on calibrated panoramic radiographs obtained before (T0) and after treatment (T1). Differences were analyzed using the Wilcoxon signed-rank and Kruskal-Wallis tests (<i>p</i> < 0.05). <b>Results</b>: Both endodontically treated and vital teeth exhibited statistically significant reductions in root length between T0 and T1 (mean reduction: 1.02 ± 1.36 mm and 1.11 ± 1.79 mm, respectively; <i>p</i> < 0.001). No significant difference was observed between the two tooth types regarding the magnitude of resorption. Similarly, no significant differences were detected among Angle Class I, II, and III malocclusion groups. The observed mean reduction of approximately 1 mm suggests limited apical shortening within the range generally considered clinically moderate. <b>Conclusions</b>: Endodontically treated teeth exhibited a degree of EARR comparable to that of vital teeth following fixed orthodontic treatment, suggesting that properly treated endodontic teeth do not pose an increased risk of clinically relevant apical root resorption during orthodontic therapy.