I compared the electrofusion (E) and polyethylene glycol induced fusion (PEG) techniques using mouse splenocytes immunized with Tca8113 cells derived from human tongue carcinoma, and produced formalin resistant monoclonal antibodies (MoAbs) against squamous cell carcinoma (SCC) using deparaffinized tissue from a formalin-fixed, paraffin-embedded block of human tongue carcinoma. Under optimal conditions for E and PEG, three MoAbs (IgM, kappa-chain), E8, P53 and P54 were isolated and characterized. E8 and P54 recognized the cytomembrane of various normal and neoplastic oral epithelial cells. Staining patterns of P53 were similar to those of several keratin MoAbs and immunoblotting assays showed multiple keratin bands of 40〜68 kDa. All three MoAbs reacted strongly with well differentiated SCC.
These antibodies may be useful as diagnostic markers.

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We attempted to examine the production of hydrolytic enzymes such as β-lactamase, DNase, hyaluronidase, chondroitin sulfatase, lipase, lecithinase, collagenase, trypsin, chymotrypsin and viscous material by clinical strains isolated from subperiosteal abscesses.
Anaerobes predominated in these isolates. The proportional distribution of β-lactamase, DNase and chymotrypsin producers were 18.5, 12.8 and 5.8%, respectively. Other hydrolytic enzyme-active bacteria were found in less than 5% of all isolates. Black-pig-mented Prevotella, especially P. intermedia predominated as β-lactamase, DNase and lecithinase producers.
These results indicate that hydrolytic enzymes produced by various Prevotella may exert an important influence on the exacerbatioh of the periapical pathosis.

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In order to investigate the developmental conditions of third molars in Japanese we studied the panoramic radiographs taken during dental treatment at the Pediatric Outpatient Section of Osaka Dental University Hospital of 9,111 (4,646 males and 4,465 females) between the ages of 7 years 0 months and 16 years 11 months, in addition to 2,769 panoramic radiographs (2,312 males and 457 females) kept by the Department of Radiology that students had taken of one another as part of their clinical studies. The following results were obtained.
1. Calcification of the third molars in both males and females began as early as 7 years 6 months in the maxilla and 7 years 0 months in the mandible. The average age for initiation of calcification in the maxilla was 9 years 4 months for males, and 9 years 2 months for females, while the ages in the mandible were 9 years 1 month and 8 years 9 months, respectively.
2. The average age for completion of the third molar crowns in the maxilla was 11 years 8 months for males and 11 years 5 months for females, while in the mandible it was 12 years 4 months and 12 years 3 months, respectively.
3. At greater than 13 years of age, the tooth germ of the third molar could be found in males about 70% of the time in the maxilla and 75% of the time in the mandible, while these figures for females were 65 and 80%, respectively.
4. All four third molars were present in 52.3% of the males and 45.5% of the females, while 9.5% of the males and 12.0% of the females had no third molars at all.
5. The direction of eruption was classified as either vertical, mesial, horizontal, distal, or buccal/lingual type. The rate for the vertical type in males was 70% in the maxilla and 45% in the mandible, while these figures for females were 50% and 40%, respectively.
6. Microdontia of the third molars appeared only in the maxilla.
7. Congenital absence of the third molars was more common in females than males, and occurred more frequently in the maxilla than in the mandible.
The results of this study allow a better understanding of the third molars of Japanese and provide an aid to planning in such areas of clinical pediatric practice as guiding occlusal development.

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Streptococcal strains with fibrous structures isolated from the dorsum of the tongue were identified and their hemagglutination and hydrophobic characteristics were examined. Morphologically different types of fibrils and fimbriae were detected in electron microscopic studies.
Identification based on both biochemical characterization and DNA homology revealed that S. salivarius and S. oralis predominated. A total of 14% of the isolates aggregated with rabbit erythrocytes. Hydrophobicity of streptococci differed in the water phase after agitation with hexadecane. The types of fibrils were related to hydrophobicity, but not hemagglutination.
Multiple factors may exist in the adherence of oral streptococci as early colonizers.

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trains of Streptococcus salivarius and oralis with fimbriae were examined for adherence to hydroxyapatite (HA) and epithelial cells, for in vitro plaque formation. The average adherence of S. salivarius to HA was 9.6×10⁵ cells/disk, while that of S. oralis with types A, D and E fimbriae were 1.7×10⁶, 4.9×10⁵ and 1.0×10⁶ cells/disk, respectively. Significantly more S. salivarius than S. oralis cells were found adhering to human oral epithelial cells. However, there was a tendency for low attachment to epithelial cells in S. salivarius strains which adhered well to HA, indicating that S. salivarius has different adherence to HA and epithelial cells. No correlation was found between adherence to HA and epithelial cells and hydrophobicity. S. salivarius had more of a capacity to form in vitro plaque than S. oralis.
These results suggest that more S. salivarius than S. oralis cells are involved in adherence.

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We made statistical observations based on the Kennedy classification of removable partial dentures (RPDs) constructed in clinical practice at Osaka Dental University Hospital between October 1987 and September 1990.
The results obtained were as follows :
1) The most common RPD was class I (861), followed by class II (661), class III (233), and class IV (83).
2) The age distribution peaked at 60〜64 years for class I, 50〜54 years for class II, 55〜59 years for class III and 60〜64 years for class IV.
3) A provisional denture was used prior to placement of the final denture in 38.9% of the maxillary class III cases, 33.9% of the maxillary class IV cases, and 29.6% of the mandibular class IV cases.
4) The arch opposing a maxillary class I or class II RPD most commonly had a new RPD, a maxillary class III or class IV RPD most commonly opposed natural dentition, a mandibular class I RPD most commonly opposed a new RPD, and a mandibular class II, III or IV RPD usually opposed natural dentition.
5) Resin plates were most frequently used as the major connector for maxillary RPDs ; palatal bars were rare, except that cast Ag-Pd-Au alloy palatal bars were used in class II RPDs. The frequency of cast palatal plates were 15.7% for class II cases and about 20% for all other classes. Resin plates were most frequently used for the mandibular major connector, followed by cast lingual bars.
6) Artificial molars were eliminated to reduce the load on the supporting soft tissues and abutment teeth in 27.3% of the maxillary class I cases, 13.4% of the mandibular class II cases, 26.9% of the mandibular class I cases and 20.8% of the mandibular class II cases.
7) Combination clasps were often used on cuspids or premolars, reflecting the effect of education on clinical practice.

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In order to assess the risk of lung diseases in dental health care workers, we measured the amounts of several metallic dusts present in the lungs of a dental laboratory technician who had died of lung cancer, using the particle induced X-ray emission (PIXE) method and radioactivation analysis. The amounts of K, Ti, Cr, Mn, Ni, Zn, Co and Au in the lungs of the technician were increased in comparison with those in the general population. Since these elements are contained in dental materials, we hope that our findings will alert dental health care workers of their possible effects on the lungs and encourage them to improve environmental hygiene in dental clinics and laboratories.

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It is well known that anaerobic bacteria, especially Bacteroides (Prevotella or Porphyromonas), Peptostreptococcus and Eubacterium are causative agents in odontogenic infections. It has been noted that hydrolytic enzyme-active P. intermedia and P. gingivalis may influence exacerbation of cases of cellulitis. We compared the isolation rate of hydrolytic enzyme-active and viscous material producing bacteria from constituents of saliva and dental plaque, chronic and acute periapical periodontitis, and subperiosteal abscesses. The severity of the disease was coincident with the isolation rate of hydrolytic enzyme-active and viscous material producing bacteria. Various enzyme producers were also found in saliva and dental plaque. These results suggest that oral flora have the potential to progress to acute odontogenic infections.

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Changes in the levels of c-fos mRNA and neuropeptide precursor mRNA in the trigeminal nucleus caudalis (TNC) in response to orofacial pain induced by the injection of 5% formalin into the facial skin of anesthetized rats were investigated by in situ hybridization histochemistry. After injection of the formalin into the upper lip, the number of neurons expressing c-fos mRNA increased, followed by increases in the number of neurons expressing preprodynorphin, preprogalanin and preprotachykinin mRNA in the superficial layers of the ipsilateral TNC. Levels of preprosomatostatin mRNA and preprocholecystokinin mRNA did not change.

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We investigated changes in the composition of the extracellular matrix (ECM), collagen, and localization of type VI collagen in a human tongue carcinoma xenograft in nude mice. We confirmed collagens of type I, III, IV and V in the xenografts by electrophoretical and immunohistochemical analyses. Although type I and type V collagens increased from five weeks after transplantation, type III collagen decreased. Type IV collagen increased gradually each week, and was localized in patches in the basement membrane. These findings indicated that while collagen functions as a scaffold to tumor cell proliferation, it proffers an adhesive environment for the cell and promotes cell-ECM interaction.

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An equimolar mixture of tetracalcium phosphate and dicalcium phosphate dihydrate, which displays solid phase buffer activity, converts to hydroxyapatite in water and sets in a short time at room temperature Cement in powder form was kneaded with Macllvaine's buffer solution and implanted in the dorsal subfascia of rats, in order to compare its histopathological effects with other endodontic sealers. Histological examinations indicated that the cement caused less infiltration of inflammatory cells into the surrounding tissue than was caused by the sealer.

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We determined the adjuvant activity of five commercially available endodontic sealers : Apatite Root Sealer Type-1 (Sankin), Canals (Syouwa), Tubli-Seal (Kerr), Sealapex (Kerr) and Dentalis KEZ (Neo). Keyhole limpet hemocyanin (KLH) served as antigen. Three of the sealers (Type-1, Canals and Tubliseal) were potent adjuvants in increasing the antibody response to KLH in C57BL/6 mice. although they did not induce IL-2 in serum. KEZ and Sealapex were not potent adjuvants in increasing IgG response to KLH, although they were potent in increasing IgM response.

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[in Japanese]

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