Purpose: The purpose of this study was to evaluate post-surgical skeletal stability in patients with facial asymmetry and canted occlusal plane.
Methods: The subjects were 7 patients who underwent bilateral sagittal splitting mandibular ramus osteotomy and Le Fort I osteotomy. Pre- and post-surgical skeletal changes were measured by frontal cephalogram. Bone fixation with mini-plates and maxillomandibular traction with elastic bands after surgery were performed. Radiographs were taken on the initial, pre-surgical and 2^nd day, and then 1, 3, 6, 12 and over 24 months after the surgery.
Results: On the 2^nd day after the surgery, the canted occlusal plane was horizontal in all of the subjects. At 6 months after the surgery, 4 of 7 cases had stabilized but 3 cases had slightly relapsed. Laterality of the lateral angle of the mandibular ramus had stabilized at 6 months after surgery. The ratio of the right and left vertical distances between the X-axis and neck point on the buccal surface of the maxillary first molar approached 1.0 in all of the subjects. On the 2^nd day after the surgery, but relapsed later. At 6 months after the surgery, the ratio had stabilized. Over 2 years after the surgery, the distance from the Y-axis to the upper and lower central incisor's midline had stabilized.
Conclusion: These results suggested that in patients having facial asymmetry with canted occlusal plane and undergoing bilateral sagittal splitting mandibular ramus osteotomy and Le Fort I osteotomy, there is some possibility of relapse in the first 6 months after surgery.

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Bite force is considered to be related to maxillofacial morphology. We investigated relationships between bite force, volume and inclination of masseter muscle and maxillofacial morphology. Subjects comprised 19 males with normal occlusion. On the sagittal view, maximum bite force was measured and the mean volume and inclination of bilateral masseter muscles were calculated. Mandibular morphology was measured using lateral cephalogram. On the frontal view, differences betweenboth sides in bite force and mandibular morphology determined from postero-anterior cephalogram were measured. The volume and inclination of masseter muscle were measured using the difference between both sides. All data were used for multiple correlation analysis.
Bite force correlated with volume of masseter muscle, Ramus plane to FH, FMA and inclination of masseter muscle. Bite force correlated with difference in ramus length, and difference in Ag height of both sides.

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The purpose of this study was to compare the changes in pharyngeal airway space after mandibular setback surgery with those after two-jaw surgery in skeletal Class III patients. Subjects were selected from consecutive patients with Class III patients treated with orthognathic surgery, and divided into two groups: 13 patients received mandibular setback surgery (MS group) and 8 patients received two-jaw surgery (TW group). First, jaw relationship, head posture, tongue positionand pharyngeal airway space were compared between two lateral cephalograms takenbefore surgery (TO) and one or more year after surgery (T1) in each group. Then, the surgical changes occuring from TO to T1 (T1-TO) were calculated and statistically compared between the two groups. As a result, jaw relationships were improved significantly in both groups after the surgery since ANB increased from TO to T1 in both groups, 5.3 degrees in the MS group and 7.1 degrees in the TW group, respectively. The head posture and tongue position did not appear to change significantly due to the surgical intervention between the two groups. The palatalpharyngeal space increased significantly in the TW group, while there was no significant post-operative difference in the MS group. On the contrary, the superior posterior pharyngeal space and middle pharyngeal space decreased significantlyin the MS group, while there was no significant post-operative difference in theTW group. All these changes showed significant differences between the two groups. On the other hand, the epiglottic pharyngeal space decreased in both groups, and the ratio was smaller in the TW group than in the MS group. In conclusion, our results indicated that two-jaw surgery actually seems to improve the jaw relationship compared to mandibular setback surgery, while the pharyngeal airway space behind the soft palate is maintained and middle airway space except for thoseis not narrower than in mandibular setback surgery. Also, the results suggest wehave to take into consideration that the pre-operative pharyngeal airway, as well as facial pattern and stability after surgery, affects the post-surgical course in orthognathic surgery of skeletal Class III patients though narrowing of thepharyngeal airway space did not cause breathing disorders.

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This clinical study was performed in order to investigate the spectrum of dentofacial deformities, management, surgical outcomes and the living area of orthognathic patients treated at Kushiro Red Cross Hospital in the eastern part of Hokkaido. Fifty-three patients were treated for dentofacial deformities in our hospital from April 1989 to December 2004. These patients have increased in recent years. There were 13 male and 40 female patients. According to clinical diagnosis and operation procedure, mandibular prognathism was the most predominant diagnosis and only sagittal split ramus osteotomy was performed in most cases. The patients lived over a wide area of eastern Hokkaido. As Kushiro Red Cross Hospital cooperats with Hokkaido University Hospital and nearby dental clinics, patients could receive the greater part of orthognathic treatments in Kushiro Red Cross Hospital. However, most patients had to go to Hokkaido University Hospital a few times. Patients could benefit from developing orthognathic management at Kushiro Red thus Cross Hospital as well as at Hokkaido University Hospital.

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We conducted maxillary distraction utilizing internal distraction devices in three patients with Apert syndrome. For these cases, we examined maxillary bone displacement, the relapse of bone distraction length and inclination changes. For this study, we chose three female patients between nine years two months and fifteen years eight months of age at the time of operation. After receiving a Le Fort III osteotomy, each patient received maxillary advancement utilizing internal distraction devices. The device was activated 1.0mm per day. After the lengthening devices were removed, the maxilla was reconstructed using poly L-lactic acid (PLLA) plates. Corresponding to pre-operation, post-operation, 1-year and 2-year post-operative periods, lateral cephalogram tracings were made. By standardizing the superimposition lateral cephalogram for the cranial base, each measurement point reflected it on the FH plane. Based on these observations, we studied the displacement in the horizontal and vertical directions of the maxilla which were indicated by point A, and we examined the inclination changes of the palatal plane based on the FH plane. As a result, the distraction lengths at point A were from 10.0mm to 14.8mm. In the two younger age groups, large differences between setting and real quantities of bone distraction lengths have not been found. Yet for the other case, actual distraction length was less than the setting length. As for the bone distraction length relapse, an average rate of 4.0% was recognized in the horizontal direction, but was not found in the vertical direction. To explain such a small relapse rate, the following reasons were discussed: longer than three months of retention period had been taken for the studies; mini-plate fixation had been applied as well as retention with the maxillary protractor; and anterior and downward growth of maxilla had taken place. The changes of the palatal plane angle had rotated counter-clockwise from 1.5° to 3.0° in the pre- and post-operative stages, and had rotated clockwise from 0.5° to 3.0° in the immediately-post and 1-year post-operative period. For the 1-year and 2-year post-operative period, a clockwise rotation rate from 1.0° to 1.5° was recognized. The palatal plane had rotated counter-clockwise after the operation, but we succeeded in achieving a relapse rate almost the same as the preoperative length.

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There are two types of operation for chin augmentation. One is augmentation genioplasty by means of horizontal osteotomy, and the other is implantation with alloplastic materials, such as silicone implants and hydroxyapatite blocks. Augmentation genioplasty with silicone implants is easy and can be performed under local anesthesia. However, augmentation genioplasty with silicone implants tends to produce post-operative infection, bone resorption of the chin, and malposition of implants. We report a case of mandibular resorption and infection following augmentation genioplasty with a silicone implant.
A 50-year-old female underwent augmentation genioplasty with silicone implantation about 8 years ago in Korea. At 7 years post-operation she noticed swelling and paresthesia in the mental region and so consulted our department. An abscess and an operative scar were observed in the intraoral mandibular incisor region. An implant was observed in the mental region, and some absorption of the bone beneath the implant radiographically. The implant was removed surgically. The implant surrounded by granulation tissue caved in the surface of the chin bone which was absorbed irregularly. These findings suggested that the resorption of surface bone under silastic implant was caused by the continuous pressure of musculus mentalis.

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A 37-year-old female suffered from facial asymmetry and malocclusion. She had undergone orthognathic surgery (sagittal split ramus osteotomy and genioplasty) at the age of 21 because of facial asymmetry.
Observation of the postoperative course was interrupted. Afterwards, facial asymmetry and the malocclusion were conspicuous, and the patient revisited our department for consultation on March 26, 2003. During the observation period (from March to December), growth of the left condylar process and malocclusion were recognized. Condylectomy was performed by an intraoral ap-proach. The resected specimen showed a thin fibrocartilage layer and dominantly consisted of mature lamellar bone tissue fragments with trabecular architecture.
According to the clinical and histopathological features, the diagnosis was condylar hyperplasia.
Exercise of Mouth-opening exercises by using a mouth gag were performed after the operation, leading to good jaw function.

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