Objectives: This study statistically observed the difference of recovery process influenced by the degree of sensory disturbance after sagittal split ramus osteotomy (SSRO).
Methods: The subjects were those who underwent SSRO, and the sensory test using Semmes-Weinstain monofilaments was conducted before and after the operation (1, 4, 8, 12 and 24 weeks after operation). Among these cases, 168 sides (106 patients) which showed a threshold rise from the preoperative value at one week after the operation were defined as sensory disturbances. These were classified into four levels (levels 1-4) according to Bell's interpretation scale. Statistical analysis was performed on the recovery period for each level and the differences in severity among different levels for each test period.
Results: Regarding the recovery period for each level, significant differences were observed (Friedman: p<0.001). No significant difference in preoperative value was seen 8 weeks after surgery for Level 1, 4 weeks for Level 2, and 24 weeks for Level 3. However, a significant difference existed at 24 weeks after surgery for Level 4 (Wilcoxon: p<0.01).In the comparison of levels for each test period, significant differences were observed for all test periods, except for before surgery (Kruskal-Wallis: p<0.01). Postoperatively, significant differences existed between Level 1 and Levels 3-4 for all test periods, and between Level 1 and Level 2 at all test periods except for 8 weeks after surgery (Mann-Whitney: p<0.01).
Conclusions: It was found that the difference in recovery period and recovery extent is influenced by the difference in level. This suggests that analysis of the recovery period with respect to degree of sensory disturbance should be useful for predicting Prognosis.

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In this study, to investigate the involvement of changes in the condylar position on mandibular stability after a sagittal split ramus osteotomy (SSRO) for mandibular prognathism, the condylar position and mandibular movement in 32 patients who underwent SSRO were radiographically examined using standard tomographs and lateral cephalometric radiographs. Subjects were separated into three groups: 8 patients who received titanium fixation, 9 patients who received poly-L-lactic acid (PLLA) fixation, and 15 patients who received wire fixation. Cephalometric analysis was evaluated preoperatively (T1), immediately after surgery (T2), and at one year after surgery (T3). Changes in condylar position were determined using tomographs at the times of T1 and T3, measuring on the right and left sides independently. The results of cephalometric analysis showed that a significant forward movement of mandible (point B) at the time of T3 was observed in the wire fixation group compared with the PLLA and titanium fixation groups, while no differences in the other cephalometric variables were indicated. Regarding changes in condylar position, no significant differences were found in the three fixation groups at the times of T1 and T3, showing similar patterns of the position changes in the three fixation groups. These results suggest that mandibular stability after SSRO is not associated with changes in condylar position or method of bone fixation.

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The purpose of this study was to clarify the positional relationship among the mandible, hyoid bone and cervical vertebrae in patients with mandibular protrusion.
Pre-and post-treatment records, including both CT images, of 11 patients were used to generate 12 angular measurements, to study the relationship among the mandible, hyoid bone and cervical vertebrae. Using a submental view of reconstructed 3DCT images obtained by CT data, an imaginary reference line was created perpendicular to the midpoint of a line tangential to the anterior borders of the right and left foramen ovale.
The results were as follows:
At the stage of pre-surgery, there was a positive correlation between the true mandible deviation and the long axis of the cervical vertebra. There was also a strong negative correlation between the true mandible deviation and the difference of the right and left axis of the mandible and cornu majus.
At the stage of post-surgery, there was a strong correlation between the angle of cornu majus change and the true mandible deviation, and the difference of the right and left axis of the mandible.
In conclusion, the results suggested that the positional relationship among the mandible, the hyoid bone, and cervical vertebrae tended to deviate in the same direction in patients with mandibular protrusion at the preoperative stage and that the cornu majus changed in the same direction as the mandible when mandibular osteotomy followed.

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We report a case of facial asymmetry treated by Walker's mandibuloplasty. This method has advantages of no orthodontic therapy and a shorter treatment period. In this case, Walker's mandibuloplasty was consistent with the patient's requests, and was useful to improve the facial asymmetry. Additionally, we used a three-dimensional model for preoperativediagnosis. Since this model showed an outline of the mandibular canal, the inferior alveolar nerve was safely moved and injury to it avoided. The model also helped to determine the resecting volume of the enlarged mandible before surgery.

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We report a patient with Crouzon syndrome and obstructive sleep apnea-hypopnea syndrome (OSAHS) treated by the Rigid External Distraction II System (RED II). The patient was an 18-year-old male. He was previously diagnosed with OSAHS in another hospital and was referred for continuation of treatment of OSAHS after changing his address. In the initial polysomnography (PSG) conducted in our hospital, the apnea-hypopnea index (AHI) was 55.9 events/hour, indicating severe OSAHS. The patient was also diagnosed with Crouzon syndrome based on facial malformation and abnormal form of craniofacial bone. For treatment, we selected bone distraction using the RED II after Le Fort III osteotomy, in order to widen the nasal airway and improve facial malformation and masticatory dysfunction. In this case, the bone distraction procedure was continued for 1 month. The treatment improved physiognomy and occlusion and reduced AHI to 25.9 events/hour after distraction.

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In cases of severe anterior cross bite caused by hypoplastic maxilla, most involving cleft lip and palate, maxillary advancement by distraction osteogenesis was performed with internal distraction devices that were fixed bilaterally on the zygoma after a high Le Fort I osteotomy. The lengthening devices were activated by 0.5 mm or 1.0mm per day. The length of maxilla ranged from 6.1mm to 14.0mm. Approximately 6 months after distraction osteogenesis of the maxilla, the lengthening devices were removed and mandibular setback was performed by sagittal split ramus osteotomy. CT images taken 6 months after maxillary advancement sho ed a bone-like radiopaque area in the pterygomaxillary junction in all three cleft lip and palate cases, whose lengthening speed was 0.5mm per day. Furthermore, no relapse was recognized in these three cases 1 year after maxillary advancement.
Regarding velopharyngeal function, hypernasality was recognized at 14mm of maxillary advancement in the cleft lip and palate cases, whereas, no hypernasality was found at under 10mm in the other cases. Velopharyngeal function might be preserved with in 10mm of maxillary advancement in cleft lip and palate cases. These findings are expected to be helpful in the consideration of the strategy of maxillary advancement by distraction osteogenesis.

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