Treatment to improve malocclusion in patients with skeletal mandibular protrusion often involves the combined use of surgical treatment in orthodontic treatment to improve not only occlusion but also facial appearance. Mandibular setback surgery is known to cause displacement of the hyoid bone and affect the morphology of the respiratory tract. However, although there have been previous reports regarding displacement of the body of the hyoid bone, few reports have verified hyoid bone rotation taking complex muscle adhesion into consideration. Therefore, the aim of the present study was to comparatively investigate the position of the hyoid bone and morphological changes of pharyngeal airway taking preoperative and postoperative inclination into consideration in patients who underwent setback of the mandible with orthognathic surgery. The subjects comprised 14 patients who underwent sagittal split ramus osteotomy to treat skeletal mandibular protrusion, exhibited at least 8.0 mm (mean: 9.0mm) of mandibular retraction with model surgery directly before surgical treatment and consented to participate after being given an outline of this study. Data comprising lateral roentgenographic cephalograms taken directly before and one year after orthognathic surgery were used to measure reference points before and after surgery and measurement items determined with the following method. When analyzing hyoid bone displacement, the hyoid bone upper projection (H1), lower projection (H2) and lowest point of the third cervical vertebra (C3) were set as reference points. Measurement items were ∠NSH1, ∠NSH2, ∠H1C3H2, C3-H1 and C3-H2. Hyoid bone rotation and displacement of the body of the hyoid bone were then evaluated. Morphology of the pharyngeal airway was analyzed by measuring respiratory tract diameter before and after surgery in the nasopharynx region, soft palate area, uvula area, angle of mandible area and epiglottis area. Results indicated that ∠NSH1 and ∠NSH2 increased significantly. However, no differences were observed in ∠H1C3H2, C3-H1 or C3-H2, with the results clarifying that the hyoid bone had moved downward and backward without rotating. Evaluation of pharyngeal airway morphology found no differences in APW1-PPW1 and APW2-PPW2, which correspond to the upper section of the pharyngeal airway but APW3-PPW3 and APW4-PPW4, which correspond to the middle section, and APW5-PPW5, which corresponds to the lower section, were found to have narrowed significantly. Accordingly, it was found that setback of the mandible with orthognathic surgery does not affect the upper section of the pharyngeal airway but does cause narrowing in the middle and lower sections due to putting pressure on the respiratory tract.

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Many patients with congenital malformation or jaw deformity exhibit craniofacial deformity. Since precise examination is essential for these cases, three-dimensional (3D) simulation models of craniofacial structure reconstructed from multi-detector computed tomography (MDCT) are frequently used. However, oral orthodontic appliances and the occlusion of upper and lower teeth make reproduction of the exact tooth shape difficult. Thus, trials are underway to generate 3D models in which the dentition reconstructed from digital imaging and communications in medicine (DICOM) data (CT data) is replaced by laser-scanned images. However, the integration accuracy and the optimum conditions for integration of MDCT and laser-scanned images are not known. Examining these points, a 3D model of craniofacial structure with accurate dentition was reconstructed in this study.
As materials, test pieces having CT values comparable to those of tooth, bone tissue and soft tissue were prepared. CT data and stereolithography (STL) data obtained from a 3D non-contact laser scanner were compared with data from an industrial μCT (true values). The optimum thresholds of test pieces were determined by comparison with those of true values. The integration accuracy was examined both by point and surface-based registration.
The different thresholds showed a wide variation in images of test pieces reconstructed from CT data, indicating that the optimum threshold is an important factor for accuracy. Using each optimum threshold, test pieces of tooth, bone tissue and soft tissue showed a high accuracy with a difference from the true value of less than 113.2μm. The difference between images from STL data and the true value was also less than 42.8μm. The surface-based registration was more reliable than the point-based registration at superimposition. In images utilizing the optimum threshold and the surface-based registration, the superimposition error between CT and STL data of the dry mandible was 173.8 and 257.8μm at the dentition and at the bone surface, respectively. The error of the patient's craniofacial structure was less than 233.8μm in the whole dentition. The present study demonstrates that acceptable craniofacial 3D images with tooth contact can be generated by optimizing various conditions.

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Facial asymmetry caused by unilateral condylar hyperplasia has been generally treated by condylectomy and/or orthognathic surgery. Here we report a case of unilateral condylar hyperplasia treated by resection of the mandibular inferior border with genioplasty for correction of facial asymmetry. A 54-year-old woman was referred to our hospital to treat asymmetry of her lower face. She had an asymmetric mandible with mental deviation resulting from hyperplastic condyle, and elongated ramus. She had Angle Class I occlusion with horizontally inclined occlusal plane. Preoperative posterior-anterior cephalogram showed hyperplasia of the left condyle and its neck with deviation of Menton (Me) to the right. Because she did not expect a change of her current occlusal condition, orthognathic surgery by bimaxillary osteotomy combined with condylectomy was refused. Alternatively, intraoral surgical resection of the mandibular inferior marginal bone and genioplasty was planned. To avoid inferior alveolar nerve injury, marginal resection of the inferior mandibular bone was limited below the mandibular canal and bone was cut by using a piezoelectric device. Although the amount of resected bone of the mandibular inferior marginal bone was restricted, she has been satisfied with her postoperative facial appearance.

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This case report describes postoperative skeletal stability in a unilateral cleft lip and palate (UCLP) patient who received maxillary distraction osteogenesis (DOG) using a rigid extraoral distractor (RED) for maxillary advancement.
The patient was a Japanese female with right UCLP who had presented at our orthodontic clinic at 5 years and 10 months of age. She received autologous secondary bone grafting (SBG) using cancellous bone from the iliac crest at 7 years and 6 months of age. Since the phase-1 orthodontic treatment to facilitate maxillary growth using a face mask did not work effectively, the objective of the phase-2 treatment was to correct midface hypoplasia.
The maxilla was advanced by DOG using RED with a significant improvement of facial esthetics and skeletal relationship. By long-term face mask therapy for 9 months, there was little postoperative relapse of maxilla in this case.
SBG and prolonged postsurgical face mask therapy are likely to improve postoperative skeletal stability in the sagittal dimension after maxillary DOG in CLP patients.

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We present three cases in whom mental disorders appeared after orthognathic surgery.
The first case was a 35-year-old female who had a history of depression. After the operation, a manic state appeared and she was diagnosed with bipolar disorder. Her medicine was changed from an antidepressant to a mood stabilizer, after which her mental condition stabilized.
The second case was a 34-year-old male. He could not accept the appearance of his postoperative face, and it took about three months for him to finally accept his new appearance.
The final case was a 37-year-old female. She could not accept the appearance of her postoperative face because it was not what she had expected. She began to complain about her face and became depressive, and was finally diagnosed with major depressive disorder. After administration of an antidepressant, her mental condition gradually improved.
We must take into consideration the possibility that patients will develop mental disorders after orthognathic surgery, and adequate explanation and patient assessment before the operation are therefore important.

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[in Japanese]

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