Evaluation of dentoalveolar structures of adult patients with skeletal class iii malocclusion requiring orthognathic surgery and adult patients with class i occlusion by cone beam computed tomography

Objective: The aim of this study was to assess the alveolar bone thickness in adult patients with skeletal Class III who require orthodontic treatment and orthognathic surgery combination by Cone-Beam Computed Tomography (CBCT) and compare the findings with those obtained from subjects with Class I occlusion. Material and Methods: CBCT images of 50 individuals were included in this study. Class III group were consisted of 30 adult patients with skeletal Class III malocclusion requiring orthognathic surgery (15 females, 15 males, mean age 22.10±3.75), and the control group were consisted of 20 adult patients (10 females, 10 males, mean age 23.55±2.51) with Class I occlusion. CBCT images of maxillary and mandibular incisors were oriented on the sagittal, coronal and axial planes by using Dolphing imaging software. Alveolar bone thicknesses of the maxillary and mandibular incisors were measured on axial sections with 3 mm intervals at buccal and lingual regions, from the cemento-enamel junction to the apical direction at three levels (gingival, middle and apical levels of roots.) Results: Alveolar bone thickness in the lingual region of all incisors was significantly greater than those in the buccal region of all incisors in both groups. Alveolar bone thicknesses of lower incisors in all lingual and buccal regions measured in Class III subjects were found significantly thinner compared to those in the control subjects, except the thinning in L2BG, L1LG and L1LO measurements did not reached statistically significant level. Buccal alveolar bone thicknesses increased and lingual alveolar bone thicknesses decreased in upper incisors of Class III subjects compared to those in the control subjects, while these changes were reached statistically significant level only in U1BO, U2BA, U2LO and U2LA measurements. Conclusion: Our findings showed that skeletal Class III subjects requiring orthodontic treatment and orthognathic surgery combination may have distinctive alveolar bone thickness, and this finding should be taken into consideration during the treatment planning of these subjects. Key Words: Alveolar bone thickness, skeletal Class III malocclusion, conebeam computed tomography