The aims of this study were to investigate the current treatment of jaw deformity in the Kyushu region in Japan and to consider the differences among surgical facilities and the discussion topics for treating jaw deformity in the region. A questionnaire survey of jaw deformity treatment between April 2014 and March 2017 was carried out and 19 surgical facilities were enrolled in the survey. The survey consisted of questions that referred to a nationwide survey performed by the Japanese Society for Jaw Deformities.
As a result, the number of patients who received orthognathic surgery was 1,579, about 68％ of whom were diagnosed with mandibular protrusion. Sagittal split ramus osteotomy （SSRO） was performed in 1,388 patients （87.9％） and Le Fort I osteotomy （LF1） in 536 patients （33.9％）. The average operation time was 163 minutes and the amount of bleeding was 172g in SSSO, and those in two-jaw surgery were 300 minutes and 434g respectively. There was a significant correlation between operation time and blood loss in two-jaw surgery （r＝0.74, p＜0.01）. Autologous blood transfusion was performed in two-jaw surgery patients by all facilities. The average duration of hospital stay was 15 days but varied by more than twenty days depending on the facility. Regarding food type after discharge, 12 facilities （70％） required patients to take chopped or soft food. All complications in this questionnaire survey were experienced. Orthodontic appliance detachment was the complication that occurred most frequently and was experienced by 12 facilities, but just 5 facilities described this in the informed consent.
This survey revealed the current status of jaw deformity treatment in the Kyushu region. We considered the values of bleeding loss and operation time in LF1 were high and that it is necessary to re-examine the procedure of LF1. The topics requiring discussion in the future are nutritional intake management and to add orthodontic appliance detachment as a complication to the informed consent.

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Masticatory function is closely related to brain function, and normal occlusion is an essential factor for favorable brain function. Mandibular prognathism （MP） shows diminished occlusal function. Jaw deformity is presumed to adversely affect brain function due to decreased occlusal function. In this study, functional near-infrared spectroscopy （fNIRS） was used to examine brain blood flow to investigate the relationship between MP and brain function.
Seventeen subjects with normal occlusion and 69 patients with MP participated in this study. The number of occlusal contacts was counted using silicone materials. Electromyography （EMG） of the masseter muscles during clenching was also recorded. Brain blood flow was measured with fNIRS during a calculation task and chewing tasks of preferential chewing of paraffin wax and hard gummy. For parametric data, Student’s t-test was used for statistical significance. The Mann-Whitney U test was used for the statistical significance of nonparametric data. The case of P＜0.05 was considered to show a statistically significant difference.
As a result, the number of occlusal contacts in MP was smaller than that in normal occlusion. Masseter muscle activity during the clenching task was weaker in MP than normal occlusion. The calculation task increased oxy-Hb in both groups. There was no significant difference in oxy-Hb between groups in the calculation task. The task of preferential chewing of paraffin wax increased oxy-Hb in both groups. This increase was significant in the bilateral inferior frontal gyrus, and interestingly, the increase was lower in MP patients than in normal occlusion. The task of chewing hard gummy also induced an increase in oxy-Hb in the bilateral inferior frontal gyrus in both groups, though the increase was lower in MP patients than in normal occlusion. Correlation analysis revealed quite a weak correlation between the number of occlusal contacts and oxy-Hb, though EMG exhibited a stronger correlation to oxy-Hb than the number of occlusal contacts.
In conclusion, compared with normal occlusion, MP patients had decreased brain blood flow during mastication in the bilateral inferior frontal gyrus, which is considered to be particularly involved in cognitive function in the prefrontal cortex. This suggests that MP may influence not only oral function but also systemic function such as brain blood flow.

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Chin augmentation using silicone implants is often performed in the field of cosmetic surgery, and has been associated with greater bone resorption and postsurgical infections. Herein, we encountered a case of bone resorption and fistula that occurred in a patient who had undergone silicone implantation at another hospital. We removed the implant and performed fistula closure using the rhomboid-to-W technique.
A 39-year-old woman visited our hospital because a fistula with pus discharge had developed in the lower portion of the mental region. Computed tomography and magnetic resonance imaging showed the presence of a silicone implant, as well as compression of the bone in the midline of the anterior region of the mandible. The fistula was contiguous with the silicone implant. Based on the medical history and image-based findings, the patient was diagnosed with an infection caused by the silicone implant. For removal of the implant and fistula closure, the rhomboid-to-W technique was applied because of the availability of a secured surgical field and consideration for postoperative esthetics. Two years after surgery, the progress remains favorable.

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