Ninety mandibular prognathism patients were radiographically assessed for condylar position and clinically evaluated for temporomandibular joint (TMJ) function before and after orthognathic surgery. Forty-five of them underwent bilateral intraoral vertical ramus osteotomies (IVRO) with passive condylar seating and no interosseous fixation. Another 45 patients underwent bilateral sagittal split ramus osteotmies (SSRO) with anterosuperiorly directed condylar seating and titanium miniplate internal fixation. Changes in condylar position following surgical-orthodontic treatment were quantified using lateral oblique transcranial radiographs of the TMJ. Condylar position in the surgical group was compared to that derived from 20 controls with normal occlusion and asymptomatic TMJs.
The following results were obtained:
1. In the surgical group before treatment, condylar postion was more broadly distributed among various positions than in the control group. There was correlation between posterior condylar position and the presence of TMJ pain or noise.
2. In the IVRO patients, the condyle exhibited significant anteroinferior displacement just after surgery. During the postoperative follow-up period, significant superoposterior movement of the condyles occurred.
3. In the SSRO patients, the condyle showed significant anterior displacement just after surgery. During the postoperative follow-up period, a slight tendency for posterior condylar movement was observed.
4. In the surgical group at the final postoperative follow-up, condylar position was similar to that in the control group. In addition, the incidence of the TMJ signs and symptoms was greatly reduced after orthognathic surgery.
The results in this study suggest that surgical correction of mandibular prognathism can improve TMJ function by repositioning the condyle to a more stable and functional position.

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We carried out immunohistochemical investigations on the relationship between the expression of E-cadherin and the clinical stage and mode of invasion of human primary oral cancers (squamous cell carcinomas).
We found that cancers having a grade 4 mode of invasion displayed a reduced type of E-cadherin expression by the classification of Shiozaki et al.
This suggests that decreased expression of E-cadherin is closely related to the high invasiveness of cancer cells.

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Linear and angular measurements of the head and neck in both the closed and maximal opening positions were taken by means of cephalometry in dental students of our school. The subjects consisted of 29 males and 31 females, without functional disorders of the masticatory system. Skeletal forms of the head and neck related to the degree of maximal opening were also investigated. The results were as follows:
1. In closed position, the position of the mandible relative to the SN plane was rotated significantly more posteriorly in females than in males.
2. The angular rotation of the mandibular ramus when the mouth was fully opened was 39.1±5.9° in males and 36.3±4.3° in females. This difference was significant (P<0.01).
3. At maximal opening, the posterior margin of the mandibular ramus came to lie near the anterior margin of the cervical spine, in nearly all subjects.
4. The correlation between the degree of the mandibular rotation and the movement of the condyle was significant (r=0.660815, P<0.01).
5. The mandibular ramus angle (SN-CGo) was correlated with the degree of movement of the condyle (r=-0.356754, P<0.01) and the rotation of the mandible (r=-0.371501, P<0.01). This implied that a decrease in the mandibular ramus angle led to an increase in maximal opening.

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The purpose of this study was to compare the proliferative activity of epithelia in odontogenic keratocysts (5 cases), follicular dental cysts (5 cases) and radicular cysts (5 cases) by using nucleolar organizer regions (Ag-NORs) and proliferating cell nuclear antigen (PCNA) in conjunction with computer-assisted imageanalysis. The following results were obtained:
The mean numbers of Ag-NORs were 2.03±0.45 in odontogenic keratocysts, 1.38±0.16 in follicular dental cysts and 1.45±0.21 in radicular cysts. The difference in the mean number of Ag-NORs between odontogenic keratocysts and the other two types of cysts was statistically significant (P<0.05).
PCNA-positive scores were 20.3±10.3% in odontogenic keratocysts, 11.7±9.9% in follicular dental cysts and 11.5±7.3% in radicular cysts. The difference in PCNA-positive score between odontogenic keratocysts and the other two types of cysts was also significant (P<0.05).
However, there was no correlation between the mean number of Ag-NORs and PCNApositive score. Thus, the epithelia of odontogenic keratocysts had high proliferative activity from the viewpoint Ag-NORs and PCNA.

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The purpose of this study was to evaluate the use of hydroxyapatite coated titanium (Ha-Ti) dental implants in graft sites of particulate cancellous bone and marrow (PCBM), with and without hydroxyapatite particles (HAP). In 76 rabbits, defects were created and restored by PCBM with (MIX group) or without (PCBM group) HAP. The implants were supported in position by titanium meshes in the mandible. In one half of the rabbits, the HA-Ti implants were placed immediately (IM group), and in the other half, the implants were placed 90 days after the graft (90D group). The animals were then killed 7, 14, 30, 60 and 90 days after placement of the HA-Ti implants. The healing process was examined histologically, and histomorphometric measurements were made using a computer-based image analyzer to quantify the rate of implant-bone bonding (IBB-ratio). In the IM and MIX groups, the IBB-ratio was lower than in the other groups in the first 30 days after implantation. After 30 days, there was very little difference in the IBB-ratios among the four groups.

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Strong and weak electric stimulations were applied to the tongues and buccal mucosae of twelve normal male adults to measure the cerebral evoked potential (CEP) and to qualitatively analyze the relationship between subjective sensitivity and the late component of CEP. The following conclusions were obtained.
1) In the CEP noted 50 to 300 msec after stimulation, four-phase waves (N1, P1, N2, and P2) were observed in all subjects. These were components of the somatosensory evoked potential (SEP).
2) In the SEP caused by electrical stimulation of the tongue, increased electric was associated with a significant increase in the amplitude between N2 and P2 (P<0.001). At peak latency, no significant difference was noted, similar to the SEP caused by electric stimulation of the buccal mucosa conducted as control.
3) Even with the same electric current, no significant difference was noted at peak latency of the SEP when electric stimulation was applied to the tongue and buccal mucosa, but highly significant differences were recognized for each amplitude (P<0.001). These results suggested that current-related variations in wave components could be examined only for SEP having the same site of stimulation.
4) In CEP caused by electric stimulation to the tongue, N100, which was a unique negative component, was recognized about 100 msec after stimulation between N1 and P1 of SEP only at the gustatory evoked potential (GEP) when electric taste was induced in the subjects. N100 reflected the information process of taste acceptance and transmission and was suggested to be a component related to the process of selecting taste quality.
5) N100 of GEP was suggested to have the potential for objective quantification of taste.

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To elucidate the mechanism of orbital floor fractures that frequently occur in conjunction with complicated fractures of the zygomaticomaxillary bone, we studied the deformation of the circumferential bones of the orbita and the orbital walls, especially the orbital floor, by strain gauge measurements made under static and dynamic loading of air-dried human skulls.
The following results were obtained:
1) Principal strains were measured under static loads applied to the infraorbital rim or zygomaticomaxillary bone and compared to those obtained when static loads were applied to the supraorbital rim. Larger principal strains were recorded when static loads were applied to the former positions, i.e., the zygomaticomaxillary suture along the facial wall and orbital wall, the maxillary-ethmoid suture, and the maxillary-lacrimal suture.
2) When static loads were applied to the area from the center to distal portions of the zygomaticomaxillary bone (i.e., the infraorbital foramen, the center of the infraorbital rim, and the body of the zygoma), large principal strains were recorded primarily on the zygomaticomaxillary suture on the infraorbital region and secondarily on the orbital wall. These findings indicate that when a force is applied to the above regions, an “impure type” inferior orbital wall fracture is prone to take place.
3) However, when static loads were applied to the medial portions of the infraorbital rim, large principal strains were recorded primarily on the orbital wall and secondarily on the infraorbital region. These results suggest that fracture of the inferior orbital wall or medial orbital wall can take place without fracture of the infraorbital rim.
4) The above results were similarly obtained by dynamic strain measurements made under impacted loads. Furthermore, under such loading, vibration of the inferior orbital wall was of greater magnitude than that of the infraorbital rim, probably because the former has large internal air spaces, i.e., the maxillary sinus and ethmoid sinus, and is constructed from thin sheet-like bones such as the ethmoidal and lacrimal bones, and the orbital wall of the maxilla or zygomatic bone.

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Deep inferior epigastric (DIE) vessels, important to vascular apastomosis of an inferior rectus abdominis free flap, were studied clinicoanatomically. This study included morphologic and morphometric examinations of the DIE artery and vein. Bifurcations of the DIE vessels, venous valves, the inner diameters of the DIE vessels, and their lengths were recorded. The following results were obtained:
1. Morphologic examination: 1) In the artery, single type (no bifurcation of the DIE artery observed) accounted for 72%. 2) In the vein, single type (no bifurcation of the DIE vein observed) accounted for 2%, distal type (two companion veins of the DIE vein come together to form one trunk before joining the external iliac vein) 33%, medial type (two companion veins of the DIE vein come together just at the point of joining the external iliac vein) 14%, and direct type (two companion veins of the DIE vein join the external iliac vein independently) 2%. 3) The DIE artery anastomosed with the superior epigastric artery in the upper abdomen. 4) Numerous surface branches of DIE arteries were evident in the paraumbilicas region. 5) Most venous valves were bicuspid. 6) Most venous valves were at the bifurcation in the distal type.
2. Morphometric examination: 1) The mean inner diameter of the DIE artery 5 mm distal from the DIE artery junction was 1.9±0.5 mm. 2) The mean inner diameters of the DIE veins 5 mm distal from the external iliac veins were 1.7±1.1 mm in the medial type, 2.5±1.5 mm in the distal type, 2.1±1.1 mm in the direct type, and 2.6 mm in the single type. 3) The maximum mean length of artery that could be used as a vascular pedicle was 12.3±2.5 cm.

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This study was designed to evaluate the in vivo affinity of titanium and stainless steel materials, the clinical use of which has remarkably increased recently, by observing the time course of tissue reactions such as reconstruction of the microvascular network in the periosteal tissue adjacent to materials implanted just be neath the mandibular periosteum in rabbits.
In this study, we used as control rabbit mandibular periosteum that had been repositioned and sutured after separation. A titanium plate and stainless plate were implanted between the mandibular periosteum and cortex. The reconstruction process of the microvascular network of the mandibular periosteum adjacent to the metal was observed over time via resin blood vessel models under scanning electron microscopy.
The results showed that microvascular reconstruction in the control mandibular periosteum was almost complet, with findings comparable to those of normal mandibular periosteum after seven days of vascular repair, which began 24 hours after injury. After titanium plate implantation, reconstruction began with repair of the outer layer in 72 hours, followed seven days later by repair of the vascular network in the inner layer. Thirty days later, reconsruction was comparable to that in the normal mandibular periosteum. In contrast, reconstruction of the microvscular network of the mandibular periosteum after stainless steel plate inplantation showed a different course. Coarse outer vascularization was noted after 30 days in the absence of inner vascular repair, although outer vascular repair had been observed seven days after metal plate implantation. These results led to the following conclusions:
1. Titanium apparently did not interfere with vascularization factors or obstruct physiological functions of the periosteum, because reconstruction of the microvascular network was observed in the mandibular periosteum exposed to the titanium plate along with signs suggestive of osteoblasts.
2. The microvascular network of the mandibular periosteum that came into contact with the stainless steel plate failed to be reconstructed and scar tissue remained. These findings suggested that vascularization factors were inhibited without recovery of the physiological function of the periosteun.

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Histologic malignancy has been reported to be one prognostic factor in patients with squamous cell carcinomas of the oral cavity. In this paper, we studied patients with oral spuamous cell carcinomas who consulted our department between 1980 and 1990 and who showed grade IV histologic malignancy (poorly differentiated, and diffusely invading squamous cell carcinoma). The results were as follows:
1. The incidence of grade IV patients was relatively low, being 7. 7%(16/208), and was almost equally distributed over primary site or T-stage.
2. The primary tumor control rate in grade IV patients was comparable to that in grade I-III patients.
3. Neck metastasis was often advanced in grade IV patients, and the control rate of neck disease was low.
4. Distant metastasis was not rare in grade IV patients.
5. The prognosis of grade IV patients was poor. The 5-year cumulative survival rate was 28.7%.
6. These findings suggest it is necessary to reconsider treatment methods of grade IV patients.

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The purpose of this study was to clarify the relationship between intracapsular adhesions in the superior compartment and clinical signs and symptoms in internal derangement of the temporomandibular joint.
The subjects were 50 consecutive closed lock cases, involving 38 unilateral and 12 bilateral joints. Their average age was 32.4 years. The intensity and extent of adhesion were quantitatively assessed by arthroscopy and compared with the patient's age, duration of locking, opening degree, visual analogue scale of pain, functional pain score, and functional disturbance score, assessed by questionnaire.
The results demonstrated negative correlations between the intensity of adhesion and opening degree, and the intensity of adhesion and functional pain score. Therefore, intracapsular adhesion may be a main cause of hypomobility. Adhesion should therefore be treated, and this may act to relieve arthralgia in closed lock of the temporomandibular joint.

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This study was undertaken to estimate the interdental alveolar bone height in regions undergoing bone grafts, and to determine what factors were correlated with the prognosis of the bone graft. A total of 120 alveolar clefts in 107 patients were studied. The alveolar clefts received grafts of autogenous particulate cancellous bone obtained from the iliac bone. The cases were documented by periapical radiographs taken before bone grafting and between 12-18 months after grafting. Successful bone formation (i.e., an interdental alveolar bone height of the grafted portion measuring more than 3/4 of the root length of the upper central incisor adjacent to the cleft), was observed in 70.8% of all clefts. The rate of successful bone formation was significantly higher in the group in which the bone graft was performed at less than ten years old than that in the older group. Unfavorable results were found at a significantly higher rate in cases in which the average width of the alveolar cleft was more than 11 mm. Thus, the age at the time of bone grafting, or the width of the alveolar cleft was definitely shown to affect the prognosis of the bone graft in the alveolar cleft. The eruption stage of the canine on the cleft side, or the cleft type, tended to be related to whether the interdental alveolar bone height was formed successfully or not.

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Carcinomas arising in the jaws are rare. The purpose of this report is to present a case of squamous cell carcinoma arising in an odontogenic keratocyst. A 72-year-old woman was referred to us for painful swelling of her left mandible with a small fistula of the surface mucosa. Radiographic examination showed an ill-defined lucent lesion in the left mandible. Segmental mandiblectomy and bilateral upper neck disection were performed based on a diagnosis of squamous cell carcinoma, determined from a biopsy specimen obtained at her former hospital. Histopathological examination of surgical specimens revealed squamous cell carcinoma as well as an odontogenic keratocyst. Furthermore, the transitional region from the cyst wall to carcinoma was clearly identified in serial sections.

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We report a case of Warthin's tumor which arose from the deep lobe of the parotid gland and extended to the parapharygeal space. A 56-year-old male was admitted because of a vague feeling of the left pharynx. MRI and CT were performed because he had lost consciousness transiently 20 days before. Examination revealed that the tumor extended from the deep lobe of the left parotid gland into the parapharyngeal space. The clinical diagnosis was a parapharyngeal tumor arising from the deep lobe of parotid gland. The tumor was surgically removed without complications by an external approach. The histopathological diagnosis was Warthin's tumor. Warthin's tumor, classified as a monomorphic adenoma, represents 4.5% to 11% of all parotid gland tumors. Warthin's tumors generally arise from the superficial lobe of the parotid gland but about 10% arise from the deep lobe.

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Carcinoma of the oral cavity arising in children is extremley rare. A case of squamous cell carcinoma of the maxillary gingiva in a 10-year-old boy is presented.
The patient visited our departmet on June 20, 1989 complaining of pain and swelling inthe labiogingival region of the right upper jaw. Clinical examination revealed a whitishverrucous growth in the right upper labial gingiva and alveolar mucosa. The growth ex-tended from the central incisor to the deciduous first molar. Radiography showed slightalveolar bone resorption in right upper lateral incisor and deciduous canine region. Inscintigraphy, there was no abnormal uptake. TNM classification was T2N0M0. Biopsyrevealed a well-differentiated squamous cell carcinoma of the gingiva. Marginal resection of the maxilla from the central incisor to the deciduous first molar was performed under generalanestheia. The patient is well without any signs of recurrence 3 years after operation.

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Pleomorphic adenomas are the most common salivary gland tumors. Of the majorsalivary glands, the predominant location is the parotid gland. Common sites of pleomorphicadenomas of the minor salivary glands are the palate, lip and buccal mucosa. Thoughpleomorphic adenoma occurs in the upper lip, it seldom occurs in the lower lip. We reporta 23-year-old female with a pleomorphic adenoma of the low lip. We do not know the re-ason why pleomorphic adenomas occur more frequently in the upper lip than the lower lip. However, there are definite differences in the distribution of the minor salivary glands betweenthe upper and lower lip, and we believe that this is one of the causes why pleomorphicadenomas seldom occur in the lower lip.

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A case of oral lichen planus (lichenoid lesions) caused by a dental nickel alloy isreported. Patch test and X-ray microanalyser (XMA) were useful in distinguishing the causa-tive metal from other dental alloys because many teeth of the patient had been repaired byvarious dental materials.

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An 84-year-old woman was referred to us on July 11, 1990 with complaints of dysphagia and a painful ulcer in the right retromolar and tonsillar areas. She had a previoushistory of surgery for tonsillar cancer (squamous cell carcinoma), followed by postoperative⁶⁰Co external irradiation to the lateral region of the neck with 50. 8 Gy and implantation of Rn-seeds about 17 years before. The postoperative course had been uneventful without re-currence or metastasis.
Oral findings showed a large ulcer of 30 mm in diameter surrounded by submucosaltumor-lke protrusion in the right retromolar and tonsillar areas. The ulcer including thesurrounding tissue was extirpated because conservative treatment had been in effective. Buthistological examination revealed nonspecific ulcer surrounded by fibrous granulation tissuewith atypical fibroblasts and hyalinization of arterioles.
Based on the patient's clinical findings, previous medical history and histological ex-amination, the lesion was diagnosed as a postradiation ulcer that appeared 17 years afterirradiation.

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We reported a very rare case of Castleman's lymphoma arising in the left parotidgland region. A 31-year-old male patient complained of swelling of the left parotidregion. The swelling was a sharply defined, elastic soft and elliptic mass measuring 28×25 mm. However, there was no tenderness or facial palsy. Sialography, CT-scan and ultrasonographywere performed. As this lesion was clinically suspected to be a benign tumor of the parotidgland, tumor enucleation was performed. Histopathological diagnosis was a hyalinevasculartype, Castleman's lymphoma. There was no evidence of recurrence in the patient 4 yearsafter operation.

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We have analysed 93 patients with mandibular angle fractures, with special re-ference to the treatment of wisdom teeth in the fracture line, during the past 6 years (1985-1990) at the Department of Oral Surgery, Ryukyu University Hospital.
The results were as follows:
1) Among 97 fracture lines in 93 cases, there were 89 wisdom teeth (91. 8%) and 31 of these were extracted.
2) Erupted teeth tended to be extracted, while premature teeth tended to be preserved.
3) There were few differences in prognosis of fractures between preserved cases and ex-tracted cases. These results suggest that the treatment of wisdom teeth should be consideedon an individual basis.

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The hyoid bone is movable and anatomically protected by the mandibule andcervica vertebrae. Hyoid bone fractures are therefore very rare.
We recently encountered a case of hyoid bone fracture which required tracheotomy andopen reduction of the upper jaw fracture.
The patent was a 44-year old male, who was strongly hit in the face by a flying tileduring typhoon No.19. A discussion of the literature is also presented.

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Adult rhabdomyoma is a rare benign tumor of striated muscle origin, which isnearly always found in the region of the head and neck.
An adult rhabdomyoma occurring in the floor of the mouth of a 76-year-old woman isreported. The tumor was surgically resected under general anesthesia on March 22, 1990. The rhabdomyoma was of lobular type and infiltrated into the genioglossus muscle.

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A dentigerous cyst associated with an odontoma in the left anterior maxilla is reported. The patient was referred to our hospital because of pain in the left anterior maxilla. Radiographic examination showed a cystic lesion with punctate opaque foci around the crown of an impacted supernumerary tooth. Histopathological examination revealed that the cyst wall was lined by non-keratinized squamous epithelium, and a small tooth-like structure was seen in fibrous connective tissue.

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