Purpose: To assess the maxillary dental arch width expansion and postoperative stability of segmental Le Fort Ⅰ osteotomy combined with horseshoe osteotomy.
Materials and methods: Seventy consecutive cases of segmental Le Fort Ⅰ osteotomy that underwent expansion of the maxillary dental arch width during the two years from January 2018 to December 2019, were examined retrospectively. Two segmental Le Fort Ⅰ osteotomy （Group A）, two segmental Le Fort Ⅰ osteotomy with parasagittal palatal osteotomy （Group B） and two segmental Le Fort Ⅰ osteotomy with additional horseshoe osteotomy （Group C） were performed to relieve the tension of the palatal mucosa. To evaluate the maxillary dental arch width expansions and expansion rates of the three groups, posteroanterior cephalograms were employed before surgery and immediately after surgery. The maxillary dental arch width was measured as the distance between the left and right outermost points of the dental arch. In addition, the maxillary dental arch widths were measured on plaster models of group C before surgery, immediately after surgery, at the end of orthodontic treatment, and at more than 1 year after the end of orthodontic treatment. To assess the postoperative stabilities of group C, the Wilcoxon signed-rank test was used to compare the relapse rates at the end of orthodontic treatment and at least 1 year after the end of orthodontic treatment.
Results: The number of cases in groups A, B and C were 32, 29 and 9, respectively. The mean expansion values of groups A, B and C on posteroanterior cephalograms were 2.3 （1.1-3.6）±0.6, 4.1 （2.9-5.4）±0.7 and 6.6 （4.8-8.8）±1.0mm; the mean expansion rates were 3.4 （1.7-5.4）±0.8, 6.1 （4.0-8.0）±1.0 and 10.0 （8.2-14.4）±1.7％, respectively. The mean relapse rates of 8 cases in group C on plaster models at two stages, the end of orthodontic treatment and at least 1 year after the end of orthodontic treatment, were 10.9 （−4.1 to 41.8）±14.9 and 15.1 （−13.3 to 35.6）±14.1％, respectively. No significant difference was observed in the relapse rates between the two stages （p＝0.547）.
Conclusion: In the segmental Le Fort Ⅰ osteotomy with horseshoe osteotomy group, more than 6mm or 8％ dental arch width expansions were obtained in the posterior part of the maxilla and good postoperative stabilities were observed.

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Introduction: In the everyday clinic, it is not unusual to come across cases diagnosed with skeletal mandibular prognathism displaying problems in the upper and lower jaw widths along with anteroposterior discrepancies. Conventionally, model analysis and lateral cephalometric analysis have been used in determining anteroposterior jaw placements when planning orthognathic surgery. However, in cases such as skeletal crossbite where improvement of the upper and lower jaw width and molar axis become necessary, it is difficult to interpret deep cranial structures using conventional frontal cephalograms, and there is no clear guideline for determining whether the problem lies in the maxillary or the mandibular arch width, or how the molar axis should be improved. Thus, this study used CBCT images of patients who underwent orthognathic surgery for correcting skeletal mandibular prognathism that displayed few signs of relapse with good stability of jaw position with more than 2 years’ retention to analyze pre- and post-treatment changes and the relationships among muscle direction, inter-molar width, and molar axis.
Materials and Methods: Twenty-one patients （6 adult men and 15 adult women with an average age of 20 years and 7 months） diagnosed with skeletal mandibular prognathism were subject to investigation. Frontal section CBCT images at first visit and after 2 years of retention were used to investigate the correlations between inter-molar width, molar axis, and inclination angles of the jaw-closing muscles following surgical mandibular setback.
Results and Conclusion: Investigation of cases with good stability after orthognathic treatment revealed a positive correlation between the inclination angles of the jaw-closing muscles and molar axis, and a positive correlation between jaw width and inter-molar width, which could be used as an index in diagnosis and treatment planning.

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This study used the national database of health insurance claims and specific health checkups of Japan （NDB）, the world’s leading public medical “big data” provided by the Ministry of Health, Labour, and Welfare, to carry out a survey with the aim of elucidating the actual situation of orthognathic surgeries performed in Japan over the past six years. The survey period was the six years between 2014 and 2019. The study revealed: 1） The number of people operated on was 16,405 patients, which increased year by year, 2） there were 4,877 male patients and 11,528 female patients （male-to-female ratio of 1: 2.4）, 3） the number of patients by age group was highest in the 20-24 year-old group, which included 4,712 patients （28.7％）, and the number of patients increased in each age group and with no changes in patient ratios according to age group, 4） regarding the number of patients according to injury or disease name, those with jaw deformity accounted for around 70％ of the study population, and it was not possible to classify patients according to detailed injury or disease name, 5） regarding the type of medical institution, around 95％ of patients were from university hospitals and general hospitals, although a small number of patients underwent surgery in clinics, 6） regarding the number of patients who were treated in hospitals by bed capacity, many patients （71.3％） were treated in hospitals with more than 200 beds, and 484 patients （3.0％） underwent treatment at clinics without inpatient facilities, 7） the number of patients by region was highest in highly populated regions like Kanto, Kinki, and Kyushu, and 8） regarding surgical techniques, 7,872 cases were treated with maxillary osteoplasty, 15,225 cases with mandibular osteoplasty, and 2,365 cases with genioplasty and anterior mandibular alveolar osteotomy. Our findings suggest that orthognathic surgery is being performed more frequently in medical institutions due to improved safety, shortened hospital stay, and higher social recognition. In addition, the use of orthognathic surgery, which can restore function and aesthetics, is expected to increase in the future.

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Patients with cleft lip and palate （CLP） often present relative skeletal mandibular prognathism. The main reason for this is the scars from lip and palatoplasty which inhibit maxillary anterior growth. The amount of forward movement of the entire maxilla by Le Fort Ⅰ osteotomy is limited to preserve the velopharyngeal function, making it difficult to achieve the ideal forward movement of the maxilla. If velopharyngeal insufficiency occurs after an ideal forward movement, pharyngoplasty is required. Because MASDO does not move the soft palate forward and does not affect the phonetic function, it is still one of the commonly used orthognathic procedures in applicable CLP cases.
In this study, we performed MASDO on a patient with inferior maxillary growth and severe crowding due to a cleft palate with good results. The patient was a phase-2 16-year-7-month-old male with a total cross bite and skeletal class Ⅲ with midfacial deficiency. In preoperative orthodontic treatment, the bilateral upper first premolars were extracted to gain space to improve the severe crowding in the maxillary dentition, and the mandible was aligned with non-extraction because of the spaced arch.
As a result of MASDO, the midfacial deficiency was improved without affecting the velopharyngeal function, and a good lateral profile was obtained. In addition, the dental arch length was enlarged, the severe anterior crowding was eliminated, and the maxillary second molars were able to be aligned. In order to align the dental midline with the facial midline, an orthodontic anchoring screw was inserted in the left molar region as a fixation source. After 2 years of retention, the width diameter of the maxillary dentition was slightly reduced, but the occlusion was stable and the facial appearance was preserved.

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It is known that stable orthodontic treatment for skeletal Class Ⅱ open-bite cases caused by retrognathia can attain over bite by mandibular counterclockwise rotation due to intrusion of upper and lower molars. Evaluation of the temporomandibular joint is essential in these cases, as there may be progressive resorption of the condyle. Furthermore, it is important to plan surgical treatment based on restoration of the mandibular position as close to the centric relation （CR） as possible. When there is disharmony in the arch width between both jaws due to a narrowed maxillary arch in adult patients, dental or skeletal expansion may be used to correct it. For skeletal expansion, distraction osteogenesis or segmental Le Fort I osteotomy is widely used. Compared to skeletal expansion, it has been reported that post-orthodontic treatment stability after orthodontic treatment is difficult to achieve with dental expansion. In this study, we report the case of a skeletal class Ⅱ open bite with posterior cross bite due to a narrow maxillary arch and CO-CR discrepancy, treated with surgical orthodontic treatment.
The patient was a 19-year-8-month-old female whose chief complaint was a protrusion of the maxillary incisors and masticatory disorder of the anterior teeth. To improve the moderate crowding and obtain an appropriate anterior tooth axis, the maxillomandibular bilateral first premolars were extracted, and preoperative orthodontic treatment was performed. Three months before orthognathic surgery, a stabilization splint was used to restore the mandibular position to the CR before determining the final amount of surgical movement of the upper and lower jaw. During surgery, the maxilla was laterally expanded by a lateral segmented Le Fort Ⅰ osteotomy and moved upward with clockwise rotation. In the mandible, it was rotated counterclockwise and set forward, resulting in an improved lateral profile and a tight occlusion. The patient is currently under retention, and the occlusion is generally maintained.

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Recently, bioabsorbable osteosynthesis materials have been improved and their use is increasing for orthognathic surgery and maxillofacial fracture because secondary operation is not necessary. However, some adverse effects have been reported, such as wound infection, failure of fixation and late-onset reaction.
We report a case of delayed-onset foreign body reaction caused by bioabsorbable plates. A 23-year-old female was referred to our department because of mandibular retrognathism. One year after maxillo-mandibular osteotomy, removal of titanium plates and genioplasty were carried out with hydroxyapatite/poly-L-lactic acid plates. Two years and 9 months after genioplasty, she re-consulted our department with pain and swelling of the chin.
A lateral cephalogram was taken at re-consultation, and showed that the chin bone fragment was stable compared with that at 6 months after genioplasty. However, dental cone beam computed tomography suggested loosening of bioabsorbable screws and plates.
There was no discharge of pus from the area of late-onset inflammatory reaction, and specific pathogens were not detected by culture analysis. We removed fragments of bioabsorbable osteosynthesis materials and granulation tissues under general anesthesia. Histopathological diagnosis was foreign granulomas. Thus, we diagnosed this case as a late-onset foreign body inflammatory reaction to hydroxyapatite/poly-L-lactic acid plates.

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Anterior maxillary osteotomies are performed to correct sagittal and vertical discrepancies in the maxilla. For the successful application of an anterior maxillary osteotomy, the molar occlusion should be stable at the time of surgery. Temporary anchorage devices （TADs） are frequently used in the treatment of orthognathic cases, affecting the treatment objectives and planning in many cases. This study reports a case of an anterior maxillary osteotomy in which maxillary molars were distalized by TADs to achieve a favorable occlusion and facial profile.
A 29-year-old woman presented to our clinic with a chief complaint of lip protrusion. The molar relationship was Angle Class II and the maxillary and mandibular incisors were significantly proclined with 15.0mm of overjet. She had large SNA and ANB angles, and was diagnosed with Angle Class Ⅱ occlusion with maxillary excess. In the presurgical orthodontics, the bilateral maxillary second molars were extracted and the bilateral maxillary first molars were distalized by using TADs. In the mandible, the bilateral first premolars were extracted, the incisors were retroclined, and the molars were mesialized. The maxillary molars were distalized by 5.5mm to achieve an Angle Class Ⅰ molar relationship. Three-dimensional surgical planning software （ProPlan CMF, Materialise） was used to simulate the surgery. During the anterior maxillary osteotomy, the bilateral maxillary first premolars were extracted. The surgery resulted in posterior movement of ANS and the maxillary incisors by 5.0 and 11.0mm, respectively.
In this case, distalization of the maxillary molars enabled a functional Angle Class Ⅰ occlusion to be a­chieved with the application of an anterior maxillary osteotomy alone. Furthermore, significant retrusion of the protruded maxillary incisors improved the facial profile with a favorable chin shape and correction of in­com­pe­tent lips. This case demonstrates that the use of TADs can improve the treatment outcome and open a new window for treatment planning and surgical options in orthognathic treatment.

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