In orthodontic treatment, Class III elastics are commonly used with a stabilizing arch wire and palatal bar for anchorage preparation before placing Class II elastics for distal movement of the anterior teeth in Class II cases. This is an important part of the Tweed technique. However, it is not clear what effect Class III elastic traction with a stabilizing arch wire has on the maxillary alveoli, or why a palatal bar is needed.
      We investigated the effect of Class III elastic traction of the maxillary dental arch on the maxillary alveoli of a dried human skull using strain gauges attached to a stabilizing arch wire.
      We found that it produced marked downward deformation with lingual bending deformation in the maxillary molar region. There was marked backward and upward deformation with buccal expansion in the alveoli anterior to the maxillary canines. In the maxilla itself, deformation-like counter clockwise rotation was noted that primarily produced a lowering of the posterior region. Deformation was smaller when traction was applied at the maxillary second molar than at the first molar. Deformation was also smaller with the palatal bar than without it.

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I analyzed the radiographic characteristics of 71 odontogenic keratocysts (OKC) from 65 patients (44 males and 21 females). The peak incidence was in the second through fourth decades of life, and the lesion was more often located in the mandible than the maxilla (44:27). The common sites were the mandibular molar-ramus (21.1%), the maxillary premolar-molar (19.7%), and mandibular incisor-premolar (14.1%) regions. Radiographically, 64.8% appeared as unilocular radiolucencies with smooth margins, which is a common presentation of jaw cysts, while 22.5% were unilocular with scalloped margins, and 12.7% exhibited a multilocular appearance. Such radiographic variations seem to have a close association with size and anatomic location. More than half of the OKCs (37) were associated with impacted teeth.
      Histologically, most of the OKC were lined by parakeratinized epithelium, which is a criterion for typical OKC, although a few were lined with orthokeratin, suggesting a distinct type of OKC.
      These results indicate that further in-depth radiographic analysis is necessary for the differential diagnosis of OKC and other jaw cysts, including dentigerous cysts.

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It is well known that sublethal heating of tumor cells results in development of transient resistance to subsequent heating, thus creating problems with hyperthermia. This phenomenon is called thermotolerance. Although its mechanism of induction and process of development are not well understood, development of drugs to block this phenomenon may be helpful in clinical application of hyperthermia.
      I investigated the effects of Cepharanthin, Apresoline and Millisrol injected intra-peritoneally for heat sensitivity and thermotolerance of human oral carcinoma (KB cells) transplanted subcutaneously in the leg of BALB/cA nude mice. The anti-tumor effect of hyperthermia with Cepharanthin, Apresoline and Millisrol was nearly 1.4, 1.8 and 1.6 fold, respectively, that of hyperthermia alone.
      Injection of each of the drugs except Cepharanthin diminished the volume of heat shock protein 70. I concluded that Apresoline and Millisrol are heat sensitization drugs, and that Cepharanthin is a heat sensitization and thermotolerance inhibition drug.

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We studied the effect on the craniofacial skeleton of rapid expansion of the maxillary arch using resistance wire strain gauges to measure the maxillary expansion forces on a dried human skull with mixed dentition. We found that the expansion created significant forces in the craniofacial skeleton, with the highest stresses being in the sutures.
      We also rapidly expanded the maxillary arch of 8 patients to investigate movement in the maxillary lateral segment, and carried out measurements on posteroanterior cephalograms, occlusal x-ray films, and dental casts. The expansion at the crowns of lateral teeth was greater than the screw expansion. The buccal tipping at the maxillary first molars was a maximum of 13.5°, a minimum of 0°, and averaged 4.57°for the 8 cases.
      We found that rapid maxillary expansion definitely caused midpalatal suture opening, although a portion of the expansion resulted from buccal tipping of the lateral segment.

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It is now recognized that sintered apatite, which has been used as an artificial dental root material, fails to induce osteogenesis in vivo. This may in part be due to its low solubility in body fluids. We developed alternative methods to produce a novel apatite that induces physiological responses as an artificial dental root material. This was done by introducing rare-earth elements into apatite by precipitation methods.
      We found considerable amounts of apatite could be obtained by the precipitation method, whereby apatite was synthesized from a mixture of calcium nitrate and phosphoric acid when sodium hydroxide was gradually added to the mixture. Rare-earth phosphate was produced in crystal form when rare-earth nitrate was present in the mixture. Further, although the precipitation method produced apatite containing rare-earth elements when a complex of rare-earth and ethylenediamine-tetraacetic acid (EDTA) was present, this combination suppressed generation of rare-earth phosphate.

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There have been many publications on recent advancements in microsurgery, and particularly on the use of the myocutaneous free flap to repair major defects in the head and neck. The value and versatility of the rectus abdominis myocutaneous free flap using microvascular surgical techniques is that it permits the transfer of a large flap in one operation. The two cases reported here deal with reconstruction of the tongue and lower face after cancer surgery.
      Case 1
      A 51-year-old male was given 30 Gy using a Cobalt 60 unit, and 5,616 cgy of interstitial Ir¹⁹² radiation because of squamous cell carcinoma of the tongue that had metastasized to the left submandibular area, mandible and skin. Wide excision of the tumor with subtotal-glossectomy produced a defect in the tongue, mandible and cutaneous tissues. A rectus abdominis free flap was transferred to the defect.
      Case 2
      A 65-year-old male with an advanced squamous cell carcinoma in the floor of the mouth (T4N2cM0) was treated by bilateral conservative neck dissection and segmental resection of the mandible with subtotal-glossectomy, after preoperative radiation of 30 Gy using a Linac unit. The defect was repaired with a rectus abdominis free flap. Wound healing and convalescence were uneventful.

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We investigated the spread of methicillin-resistant staphylococci (MRS) in Osaka Dental University Hospital. We examined the nasal carriages of the medical staff in 1994, and tested the antimicrobial susceptibility of the isolates. MRS were isolated from 70 of 93 medical staff on the first examination and 35 of 43 medical staff on the second. No MRS strains tested had mannitol fermentation or coagulase production. MRS strains were classified into various types according to antibiotic sensitivity. All MRS tested were susceptible to vancomycin. These results indicate that methicillin-resistant, coagulase-negative staphylococci of various types were prevalent in the nasal cavities of medical staff in Osaka Dental University Hospital.

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We investigated the prevalence of methicillin-resistant staphylococci(MRS) in Osaka Dental University Hospital by examining 339 locations in operating rooms, hospital wards and 7 outpatient clinics in 1994, and by testing antimicrobial susceptibility of the isolates. MRS were isolated from 25 of 110 operating room locations, 97 of l17 hospital ward locations, and 49 of 112 outpatient clinic locations. Twenty-six of the MRS strains tested had mannitol fermentation, while none had coagulase production. MRS strains were classified into various types according to antibiotic sesnitivity. All MRS strains tested were susceptible to vancomycin. These results suggest that the hospital environment in Osaka Dental University Hospital was extensively contaminated with methicillin-resistant, coagulase-negative staphylococci.

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I investigated the effects of Cepharanthin, Millisrol and Apresoline injected intraperitoneally for heat sensitivity and thermotolerance on human oral carcinoma (KB cells) transplanted subcutaneously in the leg of BALB/cA nude mice. The anti-tumor effect of hyperthermia with Cepharanthin, Millisrol and Apresoline was nearly 1.4, 1.6 and 1.8 fold that of hyperthermia alone. The volume of heat shock protein 70 was not diminished by injection of any of the drugs except Cepharanthin. I concluded that Millisrol and Apresoline are heat sensitization drugs, and that Cepharanthin is a heat sensitization and thermotolerance inhibition drug.

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We studied 27 cases of parotid tumors, which are the most common of the great slivary gland tumors. Many parotid tumors are benign pleomorphic adenoma, although some show a tendency for recurrence or malignancy, and have various clinical and pathologic presentations. As a result, their diagnosis and therapy presant many problems. We found that a few of the cases could not be accurately diagnosed by either sialograms, echograms or scintigrams. Removal of the mandible was done with the parotid surgery in three of the cases, and five required pathologic follow-up.

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I evalvated the effect of the cerebral venous return impairment in rats on the progression of ischemic lesions and cerebral edema in the acute period of focal cerebral ischemia. I prepared a model of focal cerebral ischemia by obstruction of the right common carotid artery and middle cerebral artery, and studied changes in the cerebral tissue oxygen pressure and regional cerebral blood flow during ischemia and reperfusion. The severity of cerebral edema was evaluated by measuring the specific gravity and water content of the carebral tissue. The results suggested that increase in the cerebral water content was due to an increase in the gradient of the static hydraulic pressure between the ischemic foci and surrounding tissues, and progression of cerebral ischemia. These observations underline the importance of cerebral venous pressure in ischemic cerebrovascular disorders.

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I determined the effect of the use of three experimental tannic derivatives (TAD) as primers on the adhesion of composite resin (CR) to dentin by measuring the tensile bond strength (TBS) between CR and bovine dentin treated with phosphoric acid, and examined the antibacterial activity of TAD. Application of TAD dissolved in 70% ethanol before or after phosphoric acid treatment resulted in greater TBS than when TAD was not applied. TAD showed antibacterial activity against the oral streptococci, Escherichia coli and Staphylococcus aureus when tested by three bacteriological methods. SEM revealed that bacterial cells collapsed when treated with TAD. These results suggest that TAD interfered with the creation of the layer weakened by phosphoric acid treatment, and reinforced the exposed dentinal collagen. Furthermore, the antibacterial activity of TAD seemed to inhibit secondary caries and aid in pulpal protection.

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We measured the tensile bond strength (TBS) between composite resin and bovine dentin contaminated by freshly stocked human blood or plasma. We used a commercial bonding system and observed the contaminated dentin at each step by SEM to determine the effect of the blood contamination on dentin adhesion. We found that blood contamination of ground dentin decreased TBS. No effective method of removal was found except to prepare the dentin again. Significantly lower TBS was found when the blood was removed by blowing with air rather than by rinsing with water. We also sometimes found unidentified material remaining on the contaminated dentin surface after removal procedures.

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We investigated the growth and morphological characteristics of the face and cranium of Han Chinese children with normal occlusion. We selected 180 children and divided them into six groups, three of boys and three of girls, following Hellman's developmental stages (IIIA, IIIB and IIIC). The craniofacial growth of the Han Chinese children increased forward and downward. Boys showed less growth than girls in developmental stage IIIA-IIIB. Both boys and girls showed remarkable growth in developmental stage IIIB-IIIC. The facial pattern of growth was more prominent in the mandible and less so in the maxilla. The gonial angle and mandibular plane angle of Chinese children were smaller than that of Japanese children. Han Chinese children had more prominent maxillas and mandibles than Japanese children.

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We investigated the effect of an extraoral anchorage appliance by the strain gauge method using two dry human skulls of Hellman's developmental stage VA with different palatal plane angles. We set an edgewise appliance and palatal bar on the skull and measured the strain when a 3kg force was applied to short, medium and long outer bows of a race bow headgear. The strain on the sutures was greater than the strain on the bone around the sutures. In the skull with a low palatal plane angle, even downward traction by the headgear produced backward and upward distortion of the maxilla with counter-clockwise rotation.

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I investigated the effects of a bite jumping appliance (BJA) on growing Macaca irus monkeys. The sample consisted of three monkeys, one of which was a control. Study casts and cephalometric analysis showed that after 32 weeks of active treatment, the experimental animals both had a full Class m relation in the buccal segments. The Class m relation remained during the post treatment period. Histological findings showed that growth of the post glenoid spine was different from normal growth. These results suggest that the BJA is effective for treatment of skeletal Class II malocclusions.

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We investigated the morphological changes in the dental arch and skull, and histological changes in the sutures of the nasomaxillary complex after retention following rapid platal expansion. Morphological analysis based on model measurements, frontal and lateral head x-rays, and occlusal radiography revealed that relapse occurred even in animals retained for 6 months, and that the incidence of relapse of the nasomaxillary complex increased as the retention period became shorter. Relapse occurred more frequently in the posterior region of the dental arch than in the anterior. After three months of retention, normal histological features were observed except in the frontomaxillary and frontozygomatic sutures, where there was extension of connective tissue fibers.

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I studied the effects of β-lactamase inhibitor (tazobactam, clavulanic acid and sulbactam) against β-lactamase, and investigated characterization of β-lactamase to analyze the resistance mechanism of β-lactams in Prevotella intermedia. The activity of β-lactamase, which originated in P. intermedia MA-l and its variants (v1-v11), was blocked by three inhibitors both in vivo and in vitro. β-Lactamase was purified by ion exchange column chromatography (DEAE DE-52) and gel filtration (Sephacryl S-100HR). β-Lactamase at a second peak was eluted from Sephacryl. This enzyme also showed only one peak at retention time 6'18" by HPLC (TSK gel, 2000SW column). The purified enzyme had a molecular weight of 42kDa, optimum pH of 6.0, and an isoelectric point of 8.0. Its enzyme activity was blocked by Hg^<2+>. These results suggest that P. intermedia β-lactamase is a type C cephalosporinase.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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