Avaliação tomográfica dos limites anatômicos da sínfise mandibular em pacientes adultos não-tratados ortodonticamente

Abstract

The aim of the study was to evaluate the bone limits in the region of the lower incisors by Cone Beam volume CT (CBCT), and correlate with the pattern of facial growth, with the inclination of the lower incisors, with the skeletal anteroposterior relationship and the age of patients. Tomographic images of 40 patients orthodontically untreated, have been imported into OsiriX Lite program (Pixmeo, Geneva, Switzerland), which were held multiplanar reconstructions, resulting image corresponding to the lateral teleradiography to determine the facial pattern, through the Facial Height Index (FHI). Moreover, multiplanar reconstructions were made to obtain sagittal sections in the region of the lower incisors. These images measured alveolar bone thickness in buccal, lingual, full of the lower incisors, plus the thickness measurements and total height of the mandibular symphysis. Measurements of alveolar bone thickness buccal, lingual and total were obtained at level 20, 50, 80 and 100% of the root length of the lower incisors. The results of bone measurements were correlated (Pearson correlation) with the facial pattern, with the inclination of the lower incisors, with the skeletal anteroposterior relationship and the age of patients. There were observed weak to moderate correlations among some bone measurements with facial pattern, with the inclination of the incisors and the patient's age. There was no association between the pattern of facial growth and the lingual bone thickness in the lower incisors, and was not observed association between bone measurements and skeletal anteroposterior relationship. It is believed that patients with a tendency to long-face have lesser thickness of the alveolar process of the lower incisors and greater height; patients already prone to short-face have, with rare exceptions, higher labial bone thickness and overall the level of 50, 80 and 100% of the root length.