Purpose: Orthognathic surgery to improve skeletal open bite may change the function of peripharyngeal muscles, pharyngeal airway and hyoid bone position. The purpose of this study was to investigate cephalometric changes in hyoid bone position and pharyngeal airway morphology following mandibular setback surgery in patients with skeletal open bite.
Material and Methods: The subjects were 13 patients (4 males and 9 females, mean age: 27 years 11 months) who had undergone sagittal split ramus osteotomy to improve skeletal open bite. The mean displacement of the mandible was 2.1mm posteriorly and 5.0mm superiorly after surgical intervention. Lateral cephalograms taken at pre-surgery (T1), post-surgery (T2) and 1 year after surgery (T3) were used to examine pharyngeal airway morphology and the position of the hyoid bone. The lowermost anterior edge of the third cervical vertebra (C3), the upper protruding part of the hyoid bone (H1) and the lower protruding part of the hyoid bone (H2) were defined as reference points to evaluate hyoid bone position. Anteroposterior airway width (APW-PPW) was evaluated with reference to APW1-PPW1 at the nasal pharynx, APW2-PPW2 near the soft palate, APW3-PPW3 near the uvula, APW4-PPW4 near the mandibular angle, and APW5-PPW5 near the epiglottis.
Results: ∠NSH1, ∠NSH2 and ∠H1C3H2 significantly increased in the time periods of T1-T2 and T1-T3. No significant difference was seen in C3-H1, while C3-H2 significantly decreased in the time periods of T1-T2 and T1-T3. Morphological evaluation of the pharyngeal airway did not reveal a significant difference in the upper and lower parts of the pharyngeal airway, which correspond to APW1-PPW1, APW4-PPW4 and APW5-PPW5. Stenosis was found in APW2-PPW2 and APW3-PPW3, which correspond to the middle part in the time periods of T1-T2 and T1-T3. No significant changes were seen from T2 to T3.
Conclusions: These results revealed that the hyoid bone had rotated clockwise and was displaced posteroinferiorly. Furthermore, superior displacement of the mandible causes airway stenosis at the middle part.

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A survey of orthognathic surgery in the past 16 years from 2000 to 2015, in the Department of Oral and Maxillofacial Surgery/Orthodontics, Yokohama City University Medical Center, was performed.
The results were as follows:
1. In the past 16 years, 798 patients with dentofacial deformities underwent orthognathic surgery. In the last 5 years, the average number of patients was 72.8 per year.
2. There were 247 male and 551 female patients (ratio 1：2.2).
3. The mean age at surgery was 26.6 years old.
4. The most common clinical diagnosis was mandibular protrusion without other conditions, accounting for 38.7% of the patients. Mandibular protrusion with asymmetry and asymmetry without other conditions accounted for 16.8% and 12.0%, respectively.
5. The most common surgical procedure was the combination of Le Fort I osteotomy and sagittal split ramus osteotomy (SSRO), accounting for 59.3%. SSRO accounted for only 23.7%.

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This case report describes the treatment and management of occlusion for a patient with hemifacial microsomia. A girl aged 4 years and 8 months was transferred to Tokyo Dental College, Department of Orthodontics for orthodontic diagnosis, preparation of distraction osteogenesis, and for management of occlusion during and after distraction osteogenesis. The patient was diagnosed with right hemifacial microsomia (Pruzancky grade II) with facial asymmetry and occlusal cant. In preparation for distraction osteogenesis, to enable traction from the upper-right deciduous molars to the lower-left deciduous molars, a trans-palatal arch and lingual arch were delivered to the maxillary and mandibular arch, respectively. At 6 years and 4 months, mandibular distraction osteogenesis was performed. A Zurich pediatric ramus distractor was used. Latency period was five days, and the rhythm of distraction was 0.5 mm twice a day. The direction of distraction was parallel to the mandibular ramus. The total amount of lengthening was 17 mm and the consolidation period was seven months. To keep the occlusion from changing, traction by elastics was done from the upper-right (affected side) deciduous molars to the lower-left (normal side) deciduous molars. By distraction osteogenesis, facial symmetry was obtained without destruction of occlusion such as open bite or lateral cross bite. Afterwards, an activator as a functional appliance was delivered to keep an even cant of the occlusal plane and growth was observed. However, because of the different growth potential between the normal and affected condyle, facial asymmetry recurred. Therefore, at 18 years and 7 months, two-jaw surgery was performed at Tokyo Dental College Chiba Hospital, followed by post-operative orthodontic treatment. At 19 years and 8 months retention was initiated. In cases where distraction osteogenesis is performed in the growing period, it is essential to explain beforehand that there is a possibility of recurrence of facial asymmetry and secondary surgery.

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Hyperplasia of the mandibular coronoid process is a clinical condition that causes an indolent trismus by elongated coronoid processes that impinge on the zygomatic medial surface when opening the mouth. We report a case of hyperplasia of the mandibular coronoid process which was progressive temporally and was treated by bilateral coronoidectomies.
A 10-year-old boy consulted our department with a complaint of mouth opening limitation. Maximum mouth opening (MMO) between upper and lower incisors was 20mm. Based on the image findings a diagnosis of hyperplasia of the mandibular coronoid process was made, but he and his parents did not desire treatment. Thereafter, his trismus progressed temporally and he visited our department again for treatment of hyperplasia of the mandibular coronoid process at 15 years old. The image findings showed that both enlarged coronoid processes had extended above the zygomatic arch. Bilateral coronoidectomies were performed through an intraoral approach under general anesthesia at 16 years old, and the intraoperative MMO was 50mm. Training with a mouth opening training device was started seven days after surgery, but MMO at 17 days after surgery was only 19mm. Self-training of mouth opening was continued and MMO at 15 months after surgery was 34mm. On the other hand, new island-shaped bone formation in areas of resected coronoid processes was observed on CT images three months after surgery, and the bone fragments were enlarged and connected on CT images 12 months after surgery. Therefore, continued follow-up is required for this patient.

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We describe a case in which ameloblastoma occurred in the left mandibular bone, and mandibular segmental resection was performed together with autogenous iliac bone grafting. In addition, mandibular setback was achieved by subjecting the iliac bone grafted region to an osteotomy, as the patient wanted to improve his reverse occlusion. In this report, we describe the treatment performed and analyze the resultant change in the height of the transplanted bone.
The patient was a 34-year-old male. During the first examination, multilobular radiolucent lesions were noted between the left mandibular premolar area and ramus, and a definitive diagnosis of ameloblastoma was made based on a biopsy. After resecting the tumor via mandibular segmental resection and performing plate reconstruction, secondary mandibular bone reconstruction was carried out using iliac bone grafting. Thereafter, no tumor recurrence was observed, and a partial denture was inserted in the left mandibular area. Ten years after the tumor resection procedure, the mandible was repositioned posteriorly by conducting a sagittal split ramus osteotomy on the right side and osteotomy of the iliac bone-grafted mandibular molar region on the left side to improve the patient’s reverse occlusion. The osteotomy in the bone-grafted area was performed without any problems. After surgery, the patient’s clinical course was favorable, and he did not suffer any infections or resorption of the bone graft. During the 4-year follow-up period after the mandibular setback operation, a relapse of approximately 1.5mm was noted at the menton. The patient’s postoperative course was favorable, and he was very satisfied with the treatment outcome. When iliac bone grafting is performed without a vascular pedicle, it is considered that symptoms are less likely to occur if the grafted bone is subjected to osteotomy after long-term stability has been achieved.

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Beckwith-Wiedemann syndrome (BWS) is a genetic disorder characterized by macroglossia, omphalocele, and macrosomia. Macroglossia is the predominant finding, with subsequent protrusion of dentoalveolar structures, which results in a protruding mandible, anterior open-bite, abnormally obtuse gonial angle and increased mandibular body length.
This case report describes an improvement in BWS with severe open-bite by glossectomy and orthognathic surgery.
The patient was diagnosed as BWS characterized by macroglossia, prenatal gigantism, and exomphalos at birth. There were no respiratory complications associated with macroglossia. At the age of 5, she was given the diagnosis of Wilms tumor. She underwent tumor resection in kidney and received irradiation and chemotherapy as an adjuvant treatment. She visited an orthodontic clinic with the complaint of chewing difficulty due to open-bite at the age of 12. Mandibular protrusion, spaced dental arch of the lower jaw, anterior open-bite and macroglossia were present. The molar relationship was Angle Class III. Lateral cephalometric measurement showed a skeletal Class III apical base relationship, mandibular protrusion, long mandibular length and obtuse gonial angle. Based on these findings, she was diagnosed as skeletal Class III with open-bite due to macroglossia associated with BWS. After glossectomy at the age of 12, presurgical orthodontic treatment was initiated. She underwent a second glossectomy at the age of 17 because of remaining macroglossia and exacerbated open-bite. Both glossectomies were performed at another hospital. Finally, she was referred to our hospital for orthognathic surgery at the age of 19 after pre-surgical orthodontic treatment. At this time the profile was still concave with severe open-bite. Two-jaw surgery was planned to decrease the surgical counterclockwise rotation of the mandible. Slightly modified horseshoe Le Fort I osteotomy and intraoral vertical ramus osteotomy (IVRO) were performed. Intermaxillary traction with elastics and skeletal anchorage screws was used for 6 months. The orthodontic appliance was removed 1 year after surgery. A good occlusion with molar relation of Angle Class I was acquired without sign of relapse at 2 years after surgery.

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Peripheral facial nerve palsy following orthognathic surgery is a rare complication. We discuss the incidence of this complication, its possible causes, subsequent treatment and ultimate outcomes.
A total of 910 patients underwent orthognathic surgery in our department during the period from 2001 to 2015. Five (0.55%) of those patients had peripheral facial nerve palsy postoperatively. The postoperative day when facial nerve palsy occurred ranged from day 1 to day 13. All of the cases were unilateral and included lip motility disturbance, difficulty in closing the eyes and inability to wrinkle the forehead. All of the patients received medication with an adrenocortical steroid and vitamin B₁₂. Stellate ganglion block and physical therapy were also used for the patients who had moderate to severe facial nerve palsy. Complete recovery was achieved in all but one of the patients, in whom slight palsy remained. There were several possible causes of facial nerve palsy including abnormal bleeding, postoperative swelling, and handling of operating instruments.
In conclusion, peripheral facial nerve palsy after orthognathic surgery is relatively rare. If it occurs, however, complete recovery can be expected in most cases.

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Recently, orthodontic treatment with orthognathic surgery for middle-aged and elderly patients is increasing. Almost all of these patients have a specific intraoral environment such as loss of teeth and periodontal disease. Therefore, a careful approach to the orthodontic treatment of these patients is required.
This report describes the case of a 53-year-old woman with mandibular protrusion, severe facial asymmetry, discomfort around the temporomandibular joint, missing teeth and periodontal disease.
Brushing instruction and periodontal management were provided as initial treatment. After improvement of the intraoral environment, pre-surgical orthodontic treatment was started. After 11 months of pre-surgical orthodontic treatment, intraoral vertical ramus osteotomy was performed. A skeletal anchorage system of titanium screws was used as inter-maxillary fixation for 2 weeks. Total active treatment time was 16 months.
Occlusal function and facial balance were improved by treatment with a comprehensive approach involving orthodontic, crown restoration, and periodontal management. Post-treatment records after 2 years showed good results with stable occlusion.

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