Apical root resorption after orthodontic treatment -- a retrospective study.

The purpose of the study was to compare the incidence and severity of apical root resorption in patients treated with different orthodontic appliances and to evaluate the effect of treatment duration on the degree of apical root resorption. A further aim was to analyse the degree of apical root resorption in different tooth groups in patients presenting with root resorption. The sample consisted of 625 patients (269 males, 356 females) aged 8-16 years at the beginning of treatment. Active removable plates and fixed appliances were used most frequently. Following exclusion of poor quality radiographs, the final sample included 601 patients (348 females, 253 males). Root resorption in all tooth groups, except third molars, was evaluated from pre- and post-treatment panoramic radiographs. The correlation of root resorption with treatment modality and duration was studied using multinomial logistic regression analysis. Of the tooth groups, maxillary incisors showed apical root resorption most frequently, followed by the mandibular incisors. Root resorption was significantly correlated with fixed appliance treatment (P < 0.001). In addition, the duration of fixed appliances treatment was found to contribute significantly (P < 0.01) to the degree of root resorption. The mean duration of treatment in patients without root resorption was 1.5 years, whereas in those with severe resorption was 2.3 years. The most severe resorption was seen in the maxillary incisors and premolars. It is concluded that with a long duration of fixed appliance treatment, the risk of severe resorption increases. In patients where treatment is prolonged, a 6-month radiographic follow-up is recommended.