Relationship Between Alveolar-bone Morphology Around The Mandibular Incisors And Their Inclination In Patients With Low-angle,Skeletal Class Ⅲ Malocclusion-a Retrospective CBCT Study

Objective:To quantitatively study the effect of the labial inclination of the mandibular central incisors on the surrounding cortical and cancellous-bone morphology among patients with low-angle,skeletal class Ⅲ malocclusion,by using cone-beam computed-tomography(CBCT)imaging.Methods:The CBCT images of 60 patients with low-angle,skeletal class Ⅲ malocclusion were divided into lingual-inclination,upright,and labial-inclination groups.The height of the alveolar bone and the thickness and area of the cortical,cancellous,and total alveolar bone were measured separately on each side of the mandibular central incisors.Results:The thickness of the labial cortical bone from 6 mm below the cementoenamel junction(CEJ)to the root apex;the thickness of the labial cancellous bone at the root apex;the total thickness of the alveolar bone at the root apex;the area of labial cortical bone;the total area of labial alveolar bone;and the height of the labial alveolar bone were highest in the labial-inclination group(all P<0.05).All these variables were positively correlated with the labial inclination of the mandibular central incisors(all P<0.05).There were no statistical differences between the groups for any of the measurements on the lingual side of the teeth(P>0.05).Conclusion:The morphology of the alveolar bone on the labial but not the lingual side of the mandibular central incisors was significantly correlated with the labial inclination of those teeth in patients with low-angle,skeletal class Ⅲ malocclusion.