FATORES DE PREDISPOSIÇÃO À REABSORÇÃO RADICULAR EXTERNA SEVERA ASSOCIADOS AO TRATAMENTO ORTODÔNTICO

Abstract

The external apical root resorption is often seen as an undesirable effect of orthodontic treatment, being an iatrogenic factor predictable but not avoidable. The aim of this study was to evaluate the factors common to patients who developed external root resorption moderate or severe (Malmgren's grades 3 and 4), on the maxillary incisors, during fixed orthodontic treatment in the permanent dentition. It was selected 99 patients of both genders, who began orthodontic treatment with fixed edgewise technique. Patients were divided into two groups: G1 - comprising 50 patients who completed treatment with no root resorption or presenting only apical irregularities (Malmgren's grades 0 and 1), with mean initial age of 16.79 years and mean treatment time of 3.21 years; G2 - comprising 49 patients who finished treatment presenting external apical root resorption moderate or severe (Malmgren's grades 3 and 4) on the maxillary incisors, with mean initial age of 19.92 years and mean treatment time of 3.98 years. The evaluated periapical radiographs were obtained at the beginning (T1) and at the end (T2) of orthodontic treatment. The following variables was analyzed in this study: gender, age, treatment time, type of malocclusion, treatment with or without extractions, previous trauma, degree of initial resorption, shape and root length, shape of the alveolar crest; crown:root ratio; PTV- 1 apical and incisal, ANB, Wits; 1.NA; UP + UA, overjet, overbite, FMA; PFH/AFH and H-11. Statistical analysis included chi-square tests, Fisher exact test and independent t tests. The results demonstrated the presence of a significant difference between the groups for the variables: treatment with or without extractions, initial degree of root resorption, root length and crown:root ratio at the beginning, at the end of treatment and changes with treatment, and cortical thickness of the alveolar bone. It can be concluded that are risk factors for severe root resorption in maxillary incisors during orthodontic treatment: presence of root resorption before the beginning of treatment, extractions, diminished root length, crown:root ratio decreased and thin alveolar bone at the beginning of treatment.