Radiographic examination of apical root resorption and alveolar bone loss after active phase of orthodontic therapy of malocclusions with fixed orthodontic appliances

Introduction and aim. During the active phase of orthodontic therapy of malocclusions orthodontic forces are transmitted to tooth root and adjacent alveolar bone producing tooth movement. The aim of our study is to determine whether the orthodontic forces induce resorption of root cementum and alveolar bone using orthopantomography and computerized tomography. Patients and methods. Since March 2008. until May 2012. eighty-five patients (27 male and 58 female) aged between 10 and 22 years treated with upper or/and lower fixed orthodontic appliance were included in the study. Orthopantomography was done for all patients before the beginning of orthodontic therapy and after the removal of fixed appliances and for 35 patients computerized tomography of two or three adjacent teeth was done in the same time. The tooth root length in both jaws was determined by using ortopantomography only for teeth with completed root formation. Measurements were performed for central and lateral incisors, canines, first and second premolars and first molars. The tooth root length on orthopantomograms and computerized tomograms was determined as the distance between the enamel-cementum margin and apex of tooth root. The root length for all examined teeth was measured mesially and distally directly on ortopantomograms using calibrated ruler to the nearest 0.5 mm and using i-Dixel and Syngo Fastview softver for analizes of computerized tomograms. The alveolar bone height was determined both on orthopantomograms and computerized tomograms for all examined teeth as the distance between root apex and the most coronary placed alveolar bone point with normal periodontal space width of 0.5 mm. The value of root and alveolar bone loss is determined by comparing the values of root lenght and alveolar bone height measured on orthopantomograms and computerized tomograms before and after orthodontic therapy. Finally, the changes in periodontal ligament and cortical alveolar bone width during orthodontic therapy were also determined using computerized tomography. Results. During the active phase of orthodontic treatment the most pronaunced root resorption among upper teeth was determined on second right premolars (0.6605 mm/4.3908 % mesially and 0.8661 mm/5.6738 % distally) and second (0.7274 mm/4.2264 % mesially) and first (0.6929 mm/4.3175 % distally) left premolars. The lowest value of root resorption in the upper jaw was measured on right (0.1753 mm/0.8115 % distally) and left (0.1423 mm/