The purpose of this study was to examine the reliability of applying the reference points proposed by Ritucci et al. for our the submentovertex (S-V) cephalogram, for radiographic technique. A cephalometer (Model C-166R: Tokyo-Emix Co. Ltd., Tokyo), along with an apparatus we developed, was utilized to obtain the S-V cephalograms. The S-V cephalograms of ten participants with normal occlusion (ages from 19 to 30 years) were obtained. The subjects were placed in a position with the central ray perpendicular to the Camper plane. Forty reference points on the ten films were plotted five times by an examiner, and once each by four examiners, for intra- and interexaminer reliability, respectively. Intra-examiner reliability was 0.53mm±0.25mm in the transverse plane and 0.83mm±0.79mm in the sagittal plane. Interexaminer reliability was 0.73mm±0.30mm in the transverse plane and 1.20mm±1.15mm in the sagittal plane. The most reliable point was the Foramina spinosa. This higher reliability in the intra-examiner than in the inter-examiner comparisons was statistically significant (p<0.01). Coefficient of correlations of the respective intra- and inter-examiner reliability of corresponding reference points between right and left sides were 0.97 and 0.99, which was a statistically significant finding (p<0.01). In conclusion, a clinically acceptable variation was noted in the reliability of the reference points, and each reference point had a characteristic distribution.

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Objective: To investigate the relationship between the length of the mandible and articular disc position in the temporomandibular joint using information obtained with magnetic resonance (MR) imaging and helical computed tomography (CT).
Materials and Methods: Ninety patients with jaw deformity who were candidates for surgical orthodontic treatment were examined with MRI and CT. One-hundred and eighty joints of 78 patients were classified into the following three categories according to the articular disc position observed on MR imaging: superior positioned type (type S), anterior positioned type (type A), and slightly posterior positioned type (type P). Each patient was assigned to one of six groups, according to the combination of disc positions on both TMJ's: S/S, A/A, P/P, S/A, A/P, and S/P. For 3D CT measurement of the mandibular length, the apex of the mandibular condyle (Co), the narrowest point of the mandibular incisure (In), the most lateral point on the mandibular angle (An), mental foramen (Fo), and Pogonion (Po) were assigned as reference points. Differences between Co-Po distances on both sides were evaluated as the reference for mandibular asymmetry, and correlated with articular disc position in each group. In the asymmetry group, differences between Co-In, In-An, An-Fo, and Fo-Po distances on both sides were also evaluated and correlated with articular disc position.
Results: Differences between Co-Po distances on both sides were greatest in the A/P group, followed by the S/A, S/P, A/A, S/S, and P/P groups in descending order. In every case of S/A group and P/A group, mandibular midline displacement was observed on the side of the type A disc position. In the S/P group, the mandibular midline of each case shifted toward the side of the type S disc position. The difference between Co-In distances on both sides was greatest, especially in the A/P group. Of all cases of the S/A, A/P, and S/P groups, Co-In distances were longer on the side of the type P disc position, and were shorter on the type A side.
Conclusion: The present investigation indicated that mandibular asymmetries were much greater in groups with different types of articular disc position in both joints than in groups with the same types of disc position in both joints. In groups with different types of articular disc position, it was suggested that the shorter side of the mandible might relate to the anteriorly positioned articular disc, and the longer side of the mandible might relate to the posteriorly positioned articular disc.

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[Purpose] In this study, we evaluated the usefulness of a PLLA bioabsorbable osteosynthetic plate (FIXSORB-MX^®) for bone fixation after sagittal splitting ramus osteotomy (SSRO), and the postoperative stability of the PLLA plate and a titanium mini-plate was comparatively evaluated by lateral cephalograms.
[Subjects and methods] Seventy-three patients, who received SSRO using a PLLA plate, between June 1998 and February 2000, were clinically evaluated, and physical properties of the excised PLLA plates were analyzed. Also, the postoperative stability of PLLA plates was evaluated using lateral cephalograms obtained immediately after, 6 months after, and 1 year after sugery in 10 patients who had received surgery more than 1 year previously. In addition, 10 patients received a titanium mini-plate. Patients who showed severe open bite and asymmetry of the mandible were excluded.
[Results] Of the 73 patients who received surgery using a PLLA plate, 2 showed displacement of the proximal segment, 2 developed fistulation, and 2 cases had persistent tenderness over the plate, and the plate was removed in 4 of them. The viscosity molecular weight of the plate at the removal was 60, 000, 24, 000, and 16, 000, in 3 of the 4 patients. Concerning the stability, no clear regression was observed in either the titanium mini-plate group or the PLLA plate group. From these observations, PLLA plates are considered to be clinically useful, since they are as stableas titanium mini-plates, and they do not have to be removed after implantation.

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A clinico-statistical analysis was performed on 175 cases of orthognathic surgery, in 172 patients over 20 years, at the Department of Oral and Maxillofacial Surgery, Nara Medical University. The patients were 52 males and 120 females, and the average age at surgery was 23 years old. Mandibular protrusion alone and that with asymmetry, open bite or maxillary retrusion were observed in 118 patients. Sagittal split ramus osteotomy was performed in 144 cases, and two-jaw surgery in 34 cases. Glossectomy and genioplasty were performed in 38 cases and 59 cases, respectively. Hypotensive anesthesia for reduction of blood loss was useful. A double splint technique was used for two-jaw surgery, and simulation surgery using a three-dimensional model was performed for maxillo-mandibular asymmetry. The use of an absorbable osteosynthesis system without a need for removal seemed advantageous. Hyposthesia of the lower lip was observed in 150 cases, most of which recovered in 6 months.

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In severe skeletal mandibular prognathism with soft tissue distortion, maxillary advancement, combined with mandibular set-back operation, is frequently performed to improve facial esthetics. However, few studies have been reported on the three-dimensional soft tissue changes following two-jaw surgery in Japanese subjects. Therefore, we used a threedimensional non-contact laser scanner (VIVID700^®MINOLTA) to assess presurgical and postsurgical soft tissue changes, focused on the midface. Subjects constituted five female prognathtic patients without facial asymmetry, who had received sagittal split ramus and Le Fort I osteotomies at Niigata University Dental Hospital. All cases received their preoperative and postoperative orthodontic treatment by the standard edgewise system. To standardize the scanning procedure, the VIVID700 was fixed by a special metal frame, ear rods were used to stabilize the head, and the FH plane was kept horizontal. The scanner allowed a single scan in 0.6 seconds. Presurgical and postsurgical images were taken and processed; 16 horizontal and 17 sagittal lines were constructed and were used to produce an average face for each stage. Average form showed little change in the upper region of the cheek, while the lower region of the cheek became full. In the nose area, the nose tip moved anterior and coronal, and the nasal breadth tended to widen. The upper lip moved anterior, on average.
In conclusion, although the main aim of maxillary advancement is to improve midfacial fullness, the concomitant nasal changes should be considered, and its effect on treatment outcome be ascertained.

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A clinico-statistical observation was carried out on 808 patients, who underwent orthognathic surgery between 1982 and 2001 at First Department of Oral and Maxillofacial Surgery, Osaka Dental University Hospital.
The results were as follows: 1. The number of patients with jaw deformity has increased in recent years. The total number of patients was 808 cases, about 60% of the total number of inpatients.
2. The patients were 242 males and 566 females, and the ratio of males to females was about 1: 2.3.
3. The age of patients who underwent surgery ranged from 14 to 48 years, with a mean of 21-25 years.
4. Mandibular prognathism was the most predominant diagnosis (83%).
5. Sagittal splitting ramus osteotomy (SSRO) was performed on most cases (86%).
6. The average operation time and blood loss in SSRO were 2 hr and 38 min, and 158 ml, respectively. And those in Le Fort I osteotomy and SSRO were 4 hr and 27 min, and 405ml, respectively.

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Pituitary gigantism is a rare disease that results from chronic exposure to GH (Growth Hormone). The syndrome is characterized by excessive height and growth of several tissues, including bony and soft tissues. Mandibular prognathism is often seen in the patient with pituitary gigantism. A case of pituitary gigantism accompanied by prognathism is reported here. The patient had a pituitary adenoma that caused hypersecretion of GH. Surgical resection of the pituitary adenoma, by a transsphenoidal approach, reduced the serum level of GH and Sm-C (Somatomedin-C). Preoperative orthodontic treatment started after the serum level of GH was stable and normal. Orthognathic surgery by SSRO (sagittal split ramus osteotomy) and Le Fort I osteotomy was performed, and good and satisfactory occlusion was obtained.

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A case of adult mandibular prognathism with multiple tooth loss is reported. The patient was a 32-yearold male with the chief complaint of mandibular prognathism. Intraoral examination revealed multiple tooth loss due to periodontal disease and caries, and he was diagnosed as having skeletal mandibular protrusion. After 13 months of preoperative orthodontic treatment, surgical treatment was performed, employing a sagittal split ramus osteotomy (SSRO) and rigid screw fixation between the distal and proximal segment. The setback amount was 10mm on both sides.
After surgical orthodontic treatment, the mandibular prognathism was improved. Ten months after surgical treatment, genioplasty was performed to improve the patient's facial profile. The postoperative orthodontic treatment time was 12 months. In follow-up, relapse has not been noted and occlusion remains stable. In the future, occlusion will be restored by prosthetic treatment.

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