All of the subjects that had been presented during the last 14 years in Japanese Study Group of Jaw Deformities, which was recently renamed Japanese Society for Jaw Deformities, have been reviewed in detail.
The results were as follows: 1) It is time to improve the typical operative methods. 2) Treatment of jaw deformity with the medical complications, failure cases, and long-term observed cases must be investigated. 3) Although there were many clinical presentations at the beginning, the number of basic research presentations have been increasing. 4) It seems that a long time would be required to elucidate causes and pathological conditions of jaw deformities as well as to establish preventive measures. Therefore, the current therapeutic methods, that is, “preoperative orthodontics-operation-postoperative orthodontics”, would continue to be the main stream.
We would like to establish the institution as, “Center for Jaw Deformity” to research causes and methods of treatment for severe jaw deformities. An orthognathic surgical system controlled by medical electron machines and nonsurgical treatment is expected to be developed in the future.

View full abstract

The purpose of this study was to investigate clinical application of SIS for mandibular prognathism with SIS (Severity Indicator of Soft tissue profile) to make differential diagnosis for orthognathic surgery.
The results were as follows:
1. As for the relationship between the frequency of orthognathic surgery and SIS value, the frequency of orthognathic surgery increased when SIS value decreased.
2. SIS was significantly more negative in the orthognathic surgery group (P<0.001) than in the nonsurgery group. A severer concave profile was shown in this group.
From the above, it was possible to use SIS for numerical analysis of soft tissue profile and to make accurate differential diagnosis for orthognathic surgery.

View full abstract

The purpose of this study was to clarify how to use SIS for making treatment plan of orthognathic surgery cases. The efficacy of the clinical test of the multiple regression equation was investigated.
The results were as follows:
1. SIS made it possible to evaluate the soft tissue profile numerically in both pre and posttreatment.
2. Multiple regression equation made it possible to predict the severity of the soft tissue profile in posttreatment, hence these analyses were found to be useful for making treatment plan and methods.

View full abstract

The purpose of this study was to investigate the long-term dentofacial changes following sagittal splitting ramus osteotomy in mandibular prognathism patients and to clarify morphologic factors relevant to the stability of occlusion during the retention period.
Lateral cephalograms of 19 patients (5 males and 14 females), observed for more than three years after the end of active treatment, were analyzed for evaluation of dentofacial changes. The materials were obtained at five stages: before treatment, immediately before surgery, at removal of intermaxillary fixation, at the end of active treatment and at the last. Dentofacial changes were analyzed and compared between the stages.
The results were as follows:
1. During the preoperative orthodontic treatment, the mandibular incisors were inclined labially and menton was displaced downward.
Menton was moved backward 11.1mm on average by surgery. The maxillary and mandibular incisors moved lingually and elongated during intermaxillary fixation.
During the postoperative orthodontic period, menton was displaced forward and upward (average; anteriorly 2.6mm, superiorly 0.6mm). A correlation was found between the amounts of mandibular setback and forward displacement of menton. The maxillary incisors were inclined labially.
During retention, the menton was displaced downward and mandibular incisors were slightly inclined labially.
2. Overjet and overbite tended to decrease slightly during the retention period. At the end of treatment, an acceptable occlusal relationship in the anterior region was maintained in most cases. Two patients showed edge-to-edge occlusion and one of them showed open bite.
No correlation was found between the dentofacial morphology before treatment and changes in overjet or overbite. A significant correlation was found between the amount of mandibular setback and the decrease in overbite. Vertical changes in menton and labial inclination of mandibular incisors during the retention period play a significant role in the occlusal stability after orthognathic surgery.

View full abstract

Intraoral Vertical Ramus Osteotomy (IVRO) is becoming widely used for correction of mandibular skeletal deformities in Japan.
The purpose of this study was to investigate the postoperative change of the proximal segments after bilateral IVRO. Retrospective radiographic assessments were performed for fifteen patients with mandibular prognathism who had been corrected surgically by bilateral IVRO
The results were as follows:
1. On lateral cephalometric analysis, the ramus inclination increased at one week after surgery and decreased gradually during one year.
2. On posteroanterior cephalometric analysis, Gonia showed lateral displacements at one week after surgery and returned internally during one year.
3. The condyles moved anteroinferiorly after surgery.

View full abstract

Occlusal contact was assessed and the action potentials of the masseter and temporal muscles were measured in patients with the skeletal mandibular prognathism and in healthy controls. Occlusal contact (by processing the image taken with Silicone Black) was assessed by the and image method. The action potentials of the masseter and temporal muscles were measured using a K6- I Diagnostic System The data was converted to an asymmetry index as proposed by Naei j et al., which represents the asymmetry levels of the number of contact points when biting with mild or moderate force. The asymmetry of the masseter and temporal muscles when clenching with and without cotton wadding between the teeth was also assessed using the same index. The relationship between the number of contact points and the action potentials of the muscles was analyzed using iso-probability ellipses, which had a 95% reliability.
The results were as follows:
1. Asymmetry index of the number of contact points was greater in the mandibular prognathism group than in the control group.
2. In the prognathism group, the asymmetry index of the number of contact points was less marked when biting with moderate force than when biting with mild force.
3. The muscular action potentials of patients with mandibular prognathism were not always higher on the side of the mouth with the larger number of contact points.
4. In the prognathism group, the action potentials of the temporal muscles tended to be more asymmetric than those of the masseter muscles.
5. In the prognathism group, the asymmetry of action potentials of the temporal muscles was less marked when clenching on cotton wadding.

View full abstract

This study was designed to investigate the patient's recognition of changes in facial profile due to orthognathic surgery. The results of questionnaires were summarized and analyzed in relation to cephalometric data.
The subjects consisted of forty-three posttreatment patients (13 males and 30 females) with mandibular prognathism, , who had undergone orthognathic surgery at Hiroshima University Dental Hospital. In this study, patient's recognition of improvement in facial profile was summarized in relation to morphologic changes associated with orthognathic surgery by means of Spearman's correlation analysis.
The results were as follows:
1. Before treatment, eighty-eight percent of patients were anxious about disharmony of the facial profiles, and the degree of anxiousness was severe in half of them. As for facial areas, the lower lip and chin were their greatest concern.
2. After treatment, eighty-four percent of patients recognized improvement in facial profile, and sixty-three percent of patients assessed that their profiles were improved more substantially than expected before treatment. As for facial parts, more than seventy percent of patients mainly recognized improvement in lower lip and chin.
3. The patient's recognition of improvement in facial profile, especially chin, exhibited a significantly positive correlation with the amount of mandibular setback during treatment.
These results suggested that most patients assessed that improvement in facial profile was achieved by orthognathic surgery. It is shown that their recognition of improvement in their facial profiles is significantly correlated with the amount of mandibular setback.

View full abstract

Epidemiologic study was conducted bygiving a questionnaire to 414 patients (128 males, 286 females) who indicated surgical correction of dentofacial deformity to investigate etiologic factors. The same questionnaire was given to 482 dental students as the control group and statistically compared with the patient group. The results were as follows:
1. The suggestive items of hereditary factors were recognized in the patient group, and many parents, brothers, and sisters of patients tended to have dento-facial deformity and familial congenital anomaly.
2. Many patients tended to have suffered from abnormality in their mother's body during fetal stage and birth.
3. Many patients tended to have any abnomality of skull morphology during childhood.
4. There was no significance of facial traumatic anamnesis between patient and control groups.
5. Patients who had many dental caries, oral habits, food preference, underwent orthodontic treatment or operation of jaw during childhood, and anamnesis of temporomandibular joint luxation were significantly more than those in the control group.
The results of this study revealed that dento-facial deformity was caused by hereditary and environmental factors

View full abstract

At present, clinical diagnosis of maxillofacial deformity is conducted by each institution independently and a unified classification method has not been found. Therefore, it was attempted to diagnose 26 patients who were randomly chosen using their front-facial and profile pictures from five separate institutions. It was suggested that subjective factors at each institution be included to evaluate facial form classification. Our facial form classification chart was prepared to standardize clinical diagnosis and reevaluated so that the proposed classification system could be incorporated into the clinical diagnosis method.
It is considered that the use of this chart would enable simple diagnosis of facial form without complicated analysis. The tentative plan of a facial form classification chart and facial form classification applied to the selected patients was presented. Comments regarding the proposal are solicited.

View full abstract

Various symptoms and signs of temporo-mandibular joint dysfunction have been reported following orthognathic surgery. Although the sagittal splitting ramus osteotomy, which has become one of the most common surgical procedures used for treating dento-facial deformities, has superior advantages, there is concern about pathological changes in the TMJ following surgical treatment of mandibular asymmetry. On the other hand, higher incidence of TMJ dysfunction has also been reported for mandibular asymmetry. Therefore, not only the occlusion but also improvement of TMJ dysfunction during the treatment of mandibular asymmetry must be considered.
The purpose of this study was to determine if the surgical correction of mandibular asymmetry by bilateral intraoral vertical ramus osteotomy results in improvement of symtoms. The prospective study was 23 patients (17 females and 6 males; mean age of 22.7 years) with mandibular asymmetry. History, clinical findings, and pain indices were used to determine the frequency and severity of temporomandibular joint dysfunction. The severity of the pain of temporomandibular joint dysfunction in most patients was significantly reduced or totally eliminated during the follow-up period. New symptoms and signs of TMJ dysfunction did not appear. The results supported the use of bilateral intraoral vertical ramus osteotomy during treatment of the patient with mandibular asymmetry.

View full abstract

Questionnaires were sent to oral and maxillofacial surgery, orthodontic and anesthesiology departments where board members of Japanese Association of Oral and Maxillofacial Surgeons, Japan Orthodontic Society, or Japanese Dental Society of Anesthesiology are working. Questionnaires included questions on surgical procedures for mandibular deformities, fixation methods between segments, the duration of postoperative intermaxillary fixation, complicatison of perioperative phase, and preoperative and postoperative orthodontic treatments.
This paper, as part 3 of this study, presented the results of the survey on factors affecting perioperative management of patients, intraoperative and postoperative complications, and malunion of segments based on the replies from 10 anesthesiology departments and 99 oral and maxillofacial surgery departments.
The results were as follows:
1. Thirty-four out of 71 oral and maxillofacial surgery departments suggested preoperative orthodontic treatment, the number of the teeth remaining in the oral cavity, and the size of the tongue as the most important local factors for the success of orthognathic surgery in the treatment of mandibular deformities.
2. Systemic diseases influencing surgical risk in general anesthesia were given as factors compromising perioperative patient management.
3. Sixty out of 87 oral and maxillofacial surgery departments experienced intraoperative complications. Thirty-five experienced excessive bleeding and unintentional fractures of segments during sagittal splitting osteotomy. Several departments reported experience of damage to the inferior alveolar neurovascular bundle and the facial artery and vein.
4. Seventy-six out of 90 oral and maxillofacial surgery departments reported postoperative complications. Anesthesia of the lower lip was reported by 45 departments. Infection, temporomandibular joint dysfunction, bleeding and facial nerve palsy were reported by several departments.
5. Sixteen cases of malunion between osteotomized segments were reported by 16 oral and maxillofacial surgery departments. Twelve departments reported the surgical procedures, in which seven were sagittal splitting osteotomy and five were ostectomy of the mandibular body.

View full abstract

Clinical evaluation of 107 patients who underwent orthognathic surgery was performed at of Maxillofacial Surgery, Kobe University School of Medicine between 1973 and 1991.
The results were as follows:
1. In the last eight years, the average annual number of patients was 11, about 9% of operative cases per year.
2. The age of patients who underwent surgery ranged from 16 to 38 years with a mean of 21.0 years.
3. The ratio of males to females was 1: 1.8.
4. About 90% of clinical diagnoses was mandibular prognathism.
5.(1) The predominant chief compalaint in mandibular prognathism patients was esthetic disturbance, and it was 65% in females.(2) The predominant chief complaint in mandibular prognathism with cleft lip and palate patients was masticatory disturbance (about 80%).
6. Eighty-four cases, 78.2% underwent sagittal splitting osteotomy only. Single surgery was performed on 92 cases (86.0%), which was the majority of cases.
7. Obwegeser-Dal Pont method was most frequently used in the group of sagittal splitting ramus osteotomy, but there was a tendency for that method to increase operation time and blood loss as compared with Obwegeser's original method.
8. The average posterior movement of about 6mm was accomplished Obwegeser's original method, and that of about 9mm by was Obwegeser-Dal Pont method.
9. Le Fort I osteotomy of the maxilla with lateral rotation, sagittal splitting ramus osteotomy, and intraoral horizontal ramus osteotomy (modified KosteCka's technique) were simultaneously performed on three patients with severe maxillofacial asymmetry with skeletal tilt of the occlusal plane.

View full abstract

Two hundred and thirty-one cases (223 patients) undergoing Orthognathic surgery were studied cinico-statistically between January 1985 and December 1994.
The results were as follows:
1. The number of operations have increased recently, 85% of all operations were performed during 10 recent years.
2. The ratio of male to female was 1: 1.73. The age of the cases at operation ranged from 15 to 44 years, and 135 cases (61%) were under 21 years-old.
3. The number of mandibular protrusions was 191 (86%) cases, and 58 cases (26%) were complicated with cleft anomaly.
4. According to the classification of mandibular prognathism (modified Sanborn-Hanada's classification) showed high distribution of maxillary retrusion.
5. The mandibular osteotomy was performed in 182 cases (79%), maxillary osteotomy was performed in only 12 cases (5%), and simultaneous maxillomandibular osteotomy was performed in 37 cases (16%).
6. The blood loss was 621±353ml with bilateral sagittal split ramus osteotomy (SSRO) and 1, 360±471ml with Le Fort-I osteotomy and SSRO. The operating time was 274±78 min. with SSRO and 461±81 min. with Le Fort-I osteotomy and SSRO.
7. Autologous transfusion was applied from 1988, so homologous transfusion was needed in only 3% cases undergoing SSRO and 14% of those undergoing Le Fort-I osteotomy and SSRO.

View full abstract

Obstructive sleep apnea syndrome is characterized by repeated collapse of the upper airway, producing hypopnea, apnea, and hypoxia of hemoglobin. Obstructive sleep apnea is often associated with poor dentofacial development that results in inadequate maxillomandibular space. Polysomanography was performed and the results of the preoperative stage were compared with those of the postoperative stage. This patient had mandibular skeletal deficiency, high gonial angle and a narrow posterior airway space, which were confirmed by cephalometry. In this case, PMA (prosthetic mandibular advancement) was performed as the first treatment, but no significant effect was obtained. Then mandibular advancement osteotomy and genioglossus advancement were performed. As a result, the pharyngeal muscle and base of tongue were advanced and the airway was expanded.

View full abstract