Using electromyography, I evaluated the adaptation of patients to recently placed dentures. Electromyograms (EMG) of the bilateral anterior temporal and masseter muscles were recorded in 5 patients together with mandibular kinesiograph (MKG) motions during mastication and clenching at the time of insertion of new dentures and for 4 weeks thereafter. The same recordings were made for patients who had dentures that had been in use for some time.
      EMG bursts during mastication were recorded before and after tooth contact, and the duration and integrated values were measured. EMG bursts during clenching and their integrated values were also measured. EMG burst duration and the duration preceeding tooth contact (DPTC) were longer for the new denture than with the old one for the first three days of wearing the new denture. The coefficient of variance (CV) for the EMG parameters, especially that for the burst duration and DPTC, were higher for the first three days for the new denture. After three weeks of wearing the new denture, the CV for the duration and the DPTC were lower than with the old denture. The CV for the activity preceding tooth contact (APTC) was higher for the first three days of wearing the new denture than with the old denture. EMG actvities of clenching were higher for the first three days for the new denture. After three weeks of wearing the new denture, EMG actvities of clenching were lower than with the old denture.
      The results suggest that the CV of burst duration, the CV of DPTC, and burst activities during clenching, are effective factors in evaluating patient adaptation to dentures.

View full abstract

All-ceramic crown systems that offer good esthetics and simplified fabrication techniques have recently been introduced. As an esthetic crown material, castable glass ceramic (Calcium Phosphate Crystalline Ceramic, CPCC) offers many advantages over other restorative materials, not only in strength, adaptability, and simplification of conventional laboratory procedures, but also in close reproduction of natural tooth shade. Because of its minute crystalline structure, which is similar to the enamel of natural teeth, crowns made of CPCC are strong and have good translucency. However, this translucency transmits shade differences in the underlying core material and cement.
      We investigated the effects of crystallization temperature, and the shade of various core and luting cement materials on shade reproduction in CPCC crowns. CPCC specimens (10.0×10.0×1.0mm) were fabricated at three different crystallization temperatures (635, 640 and 645℃). After examination, the CPCC specimens were placed on cores of four different shades of composite resin that had been cured with visible light, on cores of conventional chemically-cured composite resin containing silicone nitride, and on gold alloy cores. The specimens were examined both before and after luting with adhesive resin cement of three different shades. A spectrophotometer (Minolta CM-1000) was used for colorimetric analysis of the specimens, which were evaluated by the CIELAB and Munsell color system.
      We found that an increase in the CPCC crystallization temperature produced a decrease in chroma and an increase in value. When CPCC specimens were placed on core materials, there was a significant increase in value compared with that of CPCC alone. The shade of the resin cement also influenced the shade of the CPCC specimens. In particular, when opaque resin cement was placed between the CPCC specimen and the core material, there was a significant increase in value, and a yellowish hue was often observed.
      We concluded that the crystallization temperature, core shade and luting cement have considerable effect on shade reproduction in CPCC crowns.

View full abstract

We studied the relationship between mastication and salivation in cats anesthetized with urethane and chloralose. We investigated reflex salivation induced by taste, mechanical and thermal stimulation to the oral region in decerebrate cats by recording the volume of submandibular salivary secretion. Copious salivary secretion was induced when noxious thermal or mechanical stimuli were applied to the oral region. We also examined salivary secretion induced by electrical stimulation to the food intake regulating area and to the masticatory-related area in the suprabulbar structures (e.g. the lateral hypothalamic area, amygdala, coronal cortex and orbital cortex). Before immobilization, repetitive electrical stimulation of each area in these suprabulbar structures casued salivary secretion, often associated with rhythmical tongue and jaw movements resembling mastication. It was even possible to induce salivary secretion when the animals were immobilized.
      We confirmed that salivary secretion could be evoked reflexly in decerebrate animals, indicating that the medullary salivary nuclei is capable of acting as a center for reflex salivation. It is obvious, on the other hand, that suprabulbar structures act on the center in the brain stem, and that there is a close relationship between mastication and salivation.

View full abstract

Previous studies have shown that amorphous structures, which are glycoprotein in nature, surrounding vesicle-like structures in non-fimbriated Prevotella intermedia strain E18 may mediate hemagglutination. We attempted to purify a hemagglutinin from Prevotella intermedia strain E18 cells by mechanical shearing, 30-50% ammonium sulfate precipitation, 10-60% sucrose density ultracentrifugation at 35,000rpm for 20h, Arginine Sepharose 4B column chromatography, and gel filtration.
      The active fraction was eluted from an Arginine Sepharose 4B column using 1M arginine. Activity was found at the second peak on a Sepharose CL-4B column when equilibrated with 10mM tris-HC1. However, the activity at the second peak was almost lost when equilibrated with 10mM tris-HC1 containing 6M urea as a starting buffer. These purification steps resulted in an increase of specific activity from 21,400 to 118,000AU/mg. In total, the purification procedure increased the specific activity 5.5-fold that of fraction A. A single band at approximately 25kDa was obtained by SDS-PAGE. Western blotting produced single bands corresponding to those from SDS-PAGE. Protein A-gold labeling of Prevotella intermedia strain E18 cells with anti-hemagglutinin IgG revealed that the IgG bound specifically to hemagglutinin that was present on the Prevotella intermedia strain E18 cell surface. These results indicate that this protein may be a hemagglutinin.

View full abstract

Osteogenic sarcoma is a relatively rare tumor of the head and neck. Diagnosis is often difficult owing to its varied clinical and histological findings.
      The patient visited to our clinic complaining of pain in the right mandible and paresthesia of the right lower lip. Although antibiotic therapy and extraction of the tooth had been performed under a tentative diagnosis of osteomyelitis of the right mandible, there was a gradual increase in swelling of the mandible, and two weeks after the initial visit the radiograph showed the radiolucent area with a sun-ray appearance. Although two biopsies indicated that the tumor was not malignant, the final diagnosis of osteogenic sarcoma of the mandible was made from the surgical specimen. The patient died three years after the initial visit for metastasis to the lung despite good control of the primary tumor. Chemotherapy for distant micrometastasis was indicated during treatment of this tumor.

View full abstract

The "A" point, which is a reference point used in x-ray cephalometry, is regarded as the anterior boundary of the maxilla. It is used to evaluate the results of orthodontic treatment and facial growth. However, it is difficult to indicate the exact position of the "A" point on the lateral head film. We tried to identify the precise position of the "A" point on the lateral head film using a dry human skull. We found that the "A" point on the lateral head film was not always identical with the "A" point on the skull. The outline of the bone surface in front of the central incisor root ("A" point area) had two types, straight and curved. The outline of the bone surface in the "A" point area was affected by inclination of the central incisor.

View full abstract

We evaluated the growth characteristics of cells derived from the bone side (BP), middle (MP) or cementum side (CP) of the human periodontal ligament. The cells were from the mandibular right third molar and first premolar. Fifth and 15th passage cultured cells were grown in Dulbecco's modified Eagle medium containing various concentrations (5, 10 and 20%) of fetal bovine serum (FBS), and were counted at 5 and 10 days. The growth ability of the CP cells was the lowest of all examined. BP, MP and CP cells showed different growth patterns for each concentration of FBS. These results suggest that cells from different areas of the periodontal ligament produce different proliferative responses.

View full abstract

We evaluated the wettability of dentin and siliconize L-25 coated dentin (siliconized dentin) with water by measuring the contact angle. We also measured the contact angle of 4 elastomers with water and siliconize L-25. The siliconized dentin had a lower contact angle (25°) than dentin (93°). We also evaluated detail reproducibility by comparing surface roughness of dentin and stone casts made from impressions of dentin under six conditions. Spraying the denture lubricant on the dentin produced significant differences in surface roughness between the dentin and the stone casts. However, no significant difference in surface roughness was found between the dentin and the stone casts when treatment with siliconized dentin was followed by spraying with denture lubricant.

View full abstract

We evaluated the effect of irradiating tooth enamel using an Er: YAG laser with a wavelength of about 3μm to find its ability to etch enamel for resin bonding. Scanning electron microscopy and tensile bond strength test clearly showed the etching effect of Er: YAG laser irradiation. At an energy concentration or 8.5J/cm^2, the tensile bond strength was 139.7kg/cm^2, which was somewhat greater than the 118.9kg/cm^2 for acid-etched enamel. SEM images of the laser-etched enamel were very similar to those for acid etching.

View full abstract

In order to examine the application of confocal laser scanning microscopy (CLSM) to enamel caries, we compared light micrograph, microradiographs and CLSM findings of ground sections of teeth with carious lesions. Comparing light-microscopic and CLSM findings, we found strong flourescence on the body of the lesion, and weak fluorescence on the surface layer and dark zone. The translucent zone and lesion-free enamel were not found with CLSM. We concluded that CLSM is useful for observing enamel caries.

View full abstract

^<45>Ca-labeled calcium hydroxide was placed on the pulpotomy site in dog's teeth to investigate the possibility of ^<45>Ca incorporation into reparative dentin. ^<45>Ca-labeled calcium chloride was also injected intravenously following pulpotomy using nonlabeled calcium hydroxide to determine the origin of calcium in reparative dentin. Teeth containing the labeled compounds were examined autoradiographically. There was no evidence of ^<45>Ca from calcium hydroxide in the area of new dentin formation. Intravenously injected ^<45>Ca was incorporated into the dentin bridge. Calcium ions from the calcium hydroxide did not enter into formation of reparative dentin. We concluded that calcium ions necessary for calcification of new dentin were derived from the systemic circulation.

View full abstract

We observed the root surfaces of non-vital human teeth using a scanning electron microscope, and attempted to determine the relationship between root surface conditions, clinical symptoms, radiographic signs, and the status of canal obturation. Forty-eight non-vital human teeth extracted from subjects between 21 and 74 years of age were used examined. Numerous resorption lacunae were observed in the roots or teeth that had a history of discomfort. These lacunae showed smooth surface floors and sharp peripheral ridges. Cementum resorption was also observed in the roots of teeth that had no discomfort, and many of the lacunae had numerous fine particles or fiber like components on the floor or peripheral ridges.

View full abstract

We attempted to develop new root canal sealers containing calcium phosphates. Two contained α-tricalcium phosphate set by kneading with citric acid and a tannic acid solution. The other was composed of tetracalcium phosphate and dicalcium phosphate set by McIlvain's solution. We examined the physical properties of these sealers and found that they had significantly better apical sealing ability than commercially available sealers. The solubility was greater than 4% except for the tetracalcium phosphate containing sealer. Histological examination revealed that when the new sealers were implanted subcutaneously, they had less encapsulation and a milder inflammatory reaction than commercially available sealers. In addiation, the inflammatory reaction of the periapical tissue was mild to moderate, and the new sealers occasionally induced hard tissue deposition at the apex.

View full abstract

We used mercuric chloride to study the in vitro resistance of HeLa cells to mercury. Several modes of cell treatment were carried out, including a 6 hour treatment followed by either 24 or 96 hours of cultivation in fresh medium as a recovery phase. Repetition of the above combination was also done up to three times. Resistance occurred with exposure to the chemical at a level greater than 5μM. Resistance was seen with no cell recovery phase and with the 24 hour recovery phase, but not with the 96 hour recovery phase. Repeated exposure induced resistance with no cell recovery phase and with the 24 hour recovery phase. Since the resistance of cells to mercuric chloride may reflect cellular changes induced by the noxious substance, this should be taken into consideration in biomaterial testing when evaluating the physiological role of the cell.

View full abstract

We attempted to clarify the primary factors determining the timing of initial electromyographic discharges of the jaw depressor muscles (EMG-onset) by examining how to change EMG-onset by varying the duration of the open-close movement or occlusal force using the open-close-clench cycle (OCC). We also considered the effect of tooth contact and mechanoreceptors in the periodontal tissues. On both normal dentate and edentulous subjects, EMG-onset preceded initiation of opening during OCC. In normal subjects, mean masseter muscle activity associated with occlusal force was found to have significant correlation with EMG-onset. However, in open-close movement without tooth contact, EMG-onset tended to delay initiation of opening movement.

View full abstract

Normal dentate subjects were studied to determine mandibular closing positions during opening and closing movements with and without contact of the teeth. There was more variation between consecutive jaw movements in the closest position without tooth contact (CP) than with tooth contact (tapping points, TP). CP varied significantly from anterior to posterior with an increase in velocity of mandibular movement. The wider the opening distance, the greater was the lateral deviation of CP. These variations were smaller in the upright position than in the supine position. Subjects with unstable intercuspal position and an abnormal trajectory of jaw movements had larger variations in CP and TP than did normal subjects.

View full abstract

Previous study have shown that partially purified hemagglutinin isolated from non-fimbriated Prevotella intermedia strain E18 can be further purified by arginine agarose and gel filtration. We characterized a purified hemagglutinin from this strain. Hemagglutination activity was sensitive to heat and proteolytic enzymes such as trypsin, chymotrypsin and protease. Addition of D-glucosamine, D-galactosamine, N-acetylneuraminic acid, L-lysine and L-arginine caused hemagglutination inhibition, suggesting that a common component in the above sugars and amino acid may be associated with receptors for hemagglutinin. Hemagglutination activity of the hemagglutinin was eliminated by anti-hemagglutinin serum. These results indicate that non-fimbriated hemagglutinin in this study is quite similar to a hemagglutinin derived from Prevotella intermedia fimbriae.

View full abstract

We studied the cell surface of bacteria in host cells to understand the appearance of oral infectious diseases using the LUZEX-FS image processor-analyzer. Bacteria were sampled from patients with closed dentoalveolar abscesses. Gram positive and negative bacteria were observed in almost all of the abscesses used. Bacterial occupation in host cell sections was 16.7 to 27.4%, and all bacterial cells were observed in phagosomes of the host cells. Bacteria occupied 24 to 43% or the total area. A bacterial capsule was often observed on the surface of Gram negative bacteria. Vesicles originating from the outer membrane of Gram negative bactiria were about 6.lnm^2 in area. The total lysosome area occupied about 22% of the host cell cross sectional area. We confirmed that bacterial cell surface-structures could be observed in host cell samples from oral infections

View full abstract

We measured the cell envelope structures of Prevotella intermedia ATCC 25611, ATCC 33563 and Porphyromonas gingivalis 381 after shade processing and threshold setting using the LUZEX-FS image processor-analyzer. The absence or presence of certain structures were confirmed by detection of high-frequency elements of the power spectrum after Fourier transform. The width of each aspect of the 25,611 strain cell envelope was 15.3nm for the cell membrane, 7.2nm for the inner leaflet, 4.8nm for the outer leaflet, 3.3nm between the inner and the outer leaflets, and 12.4nm for the outer membrane. The widths for the 5 aspects of the 25, 611 strain were 9.8, 5.5, 2.6, 1.7 and 9.4nm by KR fixation, and 13.3, 5.5, 6.1, 1.7 and 7.7nm by FS fixation. High-frequency elements of the power spectrum after Fourier transform were detected in the peptidoglycan layer in transmission electron micrographs, and in particles on the cell surface in scanning electron micrographs. We found that the image processing system could be used to measure aspects of the bacterial cell envelope.

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract