Severe root resorption in orthodontic patients treated with the edgewise method: Prevalence and predictive factors

Introduction: Our aims in this study were to assess the prevalence of severe root resorption and identify possible associations in orthodontic patients treated with the edgewise method. Methods: The sample included 1049 patients who had periapical radiographs taken for all incisors before and after treatment. The radiographs were examined by 2 orthodontists using an x-ray viewer with standard light intensity. These variables were collected: root shape, overbite, initial resorption, and hypodontia. The patients were classified according to sex, Angle classification, ethnicity, age, duration of treatment, type of dentition (mixed or permanent), and treatment with or without extraction of 4 premolars. Resorption was considered severe when it affected more than a third of the length of the root. Statistical analysis included the chi-square test and both simple and multiple logistic regression (P <= 0.05). Results: Severe root resorption was observed in 14.5% of the sample. Patients treated with exodontia of the first premolars (odds ratio [95% CI] = 6.38 [4.2-9.7]), those who had triangle-shaped roots at the beginning of treatment (odds ratio [95% CI] = 4.67 [3.1-6.9]), and those with initial root resorption (odds ratio [95% CI] = 4.52 [2.7-7.6]) had a greater chance of developing severe root resorption during orthodontic treatment. Conclusions: A high prevalence of severe root resorption was observed in Brazilian patients treated with the edgewise method. The main factors directly involved in severe resorption were extraction of first premolars, triangle-shaped roots, and root resorption before treatment. (Am J Orthod Dentofacial Orthop 2010; 137: 384-8)