The aim of the present study was to clarify morphological differences in mandibular condyles between deviated and non-deviated sides and the spatial position of the mandible on craniomaxillary complex in a three-dimensional manner in facial asymmetry cases. A virtual reality model reconstructed from 30 patients with facial asymmetry was used in this study. The virtual reality model was segmented into two components, craniomaxillary complex and mandible, and two coordinate systems, global and local, were established in two segmented components for each of the two components. As geometric features of these virtualized models, the position and attitude of the mandible relative to the craniomaxillary complex, which represent the degree of facial asymmetry, and the angle and length of the condylar long axis, which represent the condylar morphology, were extracted. Condylar morphology was compared between the deviated and non-deviated sides. Furthermore, correlations between degrees of facial asymmetry and differences in condylar morphology between the deviated and non-deviated sides were examined. The results were as follows: (1) the length of the condylar long axis on the deviated side was significantly smaller than that on the non-deviated side; (2) the difference in the length of the condylar long axis increased with an increase of lateral deviation of the mandible; (3) the angle of the condylar axis on a Md axial plane on the deviated side was significantly larger than that on the non-deviated side; and (4) the difference in angle of the condylar long axis tended to increase with an increase of relative attitude of the mandible toward craniomaxillary complex on the axial plane. The results obtained from the 3D analysis method for which a reference coordinate system was established in the mandible itself indicated close relationships between bilateral morphological differences in the condyles and facial asymmetry.

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Clinical analysis was performed for 1,448 patients with jaw deformities who had undergone orthognathic surgery in our hospital over the past 48 years. The patients included 473 males and 975 females with a mean age at the time of operation of 22 years (range: 12–55 years). About 90% of the patients were under 30 years of age. The most common clinical diagnosis was mandibular prognathism (796 cases), and the percentage of patients with maxillary protrusion or mandibular retrognathism (96 cases) was low. Sixty patients had congenital disorders and ten had traumatic injuries. The most common surgical method was sagittal split ramus osteotomy (SSRO), and the combination of Le Fort I osteotomy and SSRO (L1+SSRO) was the second-most common surgical method. The average operation time and amount of bleeding for SSRO were 186.0±93.0 minutes and 453.8±396.9ml, respectively, and those for L1+SSRO were 232.4±80.1 minutes and 621.9±423.1ml, respectively. Blood transfusion was performed in about 70% of the patients, and the most common type was autologous blood transfusion. The average amounts of blood transfusion in SSRO and L1+SSRO were 261.8±343.9ml and 520.7±286.9ml, respectively.
More complicated surgical techniques have been used over the years in order to meet the expectations of patients with jaw deformities. Operative time and amount of bleeding have increased as the surgical techniques have become more complicated. We have attempted to shorten the operative time and decrease the amount of bleeding by improving the technical skills of surgeons and introducing new surgical instruments.

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When maxillary downgraft is performed for patients with severe maxillary deficiency, postoperative stability is sometimes insufficient. We report a case of mandibular protrusion with excessive vertical maxillary deficiency treated with simultaneous maxillo-mandibular distraction osteogenesis using alveolar distractors.
A 25-year-old male patient visited our orthodontic clinic for treatment of his chief complaint that his upper incisors were invisible upon smiling. Upon examination, he was diagnosed as mandibular overgrowth with excessive vertical maxillary deficiency. Simultaneous maxillo-mandibular distraction osteogenesis was performed for considerable downward movement of the maxilla. Le Fort I osteotomy and bilateral inverted L osteotomy of the mandible were performed under general anesthesia. Bilateral alveolar distractors were set to the maxilla. After maxillo-mandibular fixation, distraction osteogenesis was performed downward by 10.5mm. Although slight relapse occurred 1 year after surgery and the final total amount of distraction was 9.0mm, the facial height and profile were improved and adequate exposure of the upper incisors was obtained.

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In patients with skeletal maxillary protrusion caused by severe mandibular deficiency, surgical orthodontics involving mandibular body distraction osteogenesis are sometimes selected depending on the amount of forward displacement of bone fragments and the severity of temporomandibular joint symptoms. Distraction osteogenesis can accelerate new bone formation at the lengthened portion and extension of the surrounding soft tissue, however, there are few reports of long-term follow-up cases. Here we report on the 10-year follow-up of a patient with severe mandibular deficiency and mandibular deviation toward the left side, who underwent mandibular body distraction osteogenesis followed by retention.
The patient was a 21-year-old Japanese female. After pre-surgical orthodontic treatment for 1 year and 6 months, distraction osteogenesis and genioplasty were performed. The mandibular body was lengthened by 7.0mm on the right side and 9.5mm on the left side. Postsurgical orthodontic treatment was combined with the use of intermaxillary elastic for approximately 8 months.
The duration of active treatment was 2 years and 4 months and the Angle Class I relationship was obtained with appropriate incisal relationships. Mandibular body distraction osteogenesis and genioplasty improved anteroposterior disharmony between the maxilla and the mandible, chin recession, and mandibular shift to the left side. The patient underwent approximately 6 years of mechanical retention followed by natural retention. Ten years after starting retention, the mandibular midline had shifted 1.5mm to the left and only slight relapse of the mandibular position was recognized. Occlusal relationships were maintained with few changes in overjet of 0.5mm. No marked morphological changes were recognized in the mandibular condyle. Stable occlusion obtained from the active treatment and less change in the condylar morphology during the retention seem to contribute to the long-term stable treatment results.

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