Tooth root and alveolar bone grey values derived from cone-beam CT imaging in maxillary incisor teeth with and without apical root resorption.

INTRODUCTION: In orthodontic treatment, an increased bone mineral density of the alveolar bone is considered as a risk factor for apical root resorption (ARR), whereas the mineral density of cementum has been associated with root protection against resorption. METHODS: This study aimed at evaluating the grey values (GVs) of the apical third of the root and of the alveolar bone adjacent to maxillary incisors with and without ARR in orthodontic patients. Twenty-one patients under treatment who presented one incisor with ARR and its corresponding contralateral without ARR were selected and submitted to cone-beam computed tomography. GVs were evaluated on the images obtained of four areas of the apical third of the root and of four areas of the adjacent alveolar bone. RESULTS AND CONCLUSIONS: The radicular tissue of the apical third of the incisors with ARR showed greater root GV (p < .05) than that of the incisors without ARR. Supra-apical alveolar bone exhibited greater GV in the incisors without ARR than incisors with ARR (p < .05). Root GV was not associated with root protection, but rather seemed to have facilitated the process of resorption. The GV of the lingual bone was associated with a higher progression of ARR in the incisors.