Comparative Study of Mandible Ramus Morphology Using 3-dimensional CT in Sagittal Split Ramus Osteotomy

The purpose of the present study was to investigate the relevance of the external morphology of the mandibular ramus, internal bone tissue structure, and maxillofacial morphology at the site for sagittal split ramus osteotomy among different facial skeletal patterns. A total of 80 patients with jaw deformities who underwent sagittal split ramus osteotomy were included in the study. The patients were divided into two groups based on facial skeletal type (skeletal Class II or skeletal Class III). A further 7 patients with no skeletal abnormalities were established as the control group (skeletal Class I). Computed tomography images obtained from these patients were 3-dimensionally reconstructed and the morphology of the mandibular ramus determined. Thickness at the mandibular foramen in Class II was greater than that in Class III, and showed the lowest value at the midpoint of the mandibular foramen and mandibular notch in Class I. Mandibular morphology showed change according to facial skeletal type. Correlations were also observed between the cephalometric analysis values and mandibular morphology.