The glycation levels were investigated in collagen extracted from masticatory mucosa of streptozotocin-induced diabetic and age-matched control rats in order to elucidate the nonenzymatic glycation, referred to as the Maillard reaction, in the collagen of diabetic animals. Early-stage products of the Maillard reaction were measured by furosine, which is an acid hydrolysis product derived from fructose-lysine. Late-stage products of the Maillard reaction were measured with fluorescence as an indicator.
The total hydroxyproline in the masticatory mucosa of diabetic rats decreased relative to the controls. Furthermore, solubilization of the collagen by pepsin and the type III/I ratio of collagen decreased in the diabetic rats. Furosine levels did not correlate with serum glucose levels, and no difference was seen between the two groups in the level of furosine. Although the fluorescence intensity in the controls did not correlate with serum glucose levels, they did in the diabetic group. The fluorescence intensity in the diabetic animals increased relative to that in the controls.
These findings suggest that the effects of the high serum glucose level extend to the collagen which makes up the extracellular matrix of the masticatory mucosa. The apparent acceleration of high glycosylated collagen in diabetes may contributed to the development of cross-linkage in collagen.

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We studied the effects of dynamic extraction on cytotoxicity and dissolution of metallic biomaterials for dental restorations under stress by gyrating them on alumina balls for seven days in distilled water, Ringer's solution, phosphate buffered saline, Eagle's minimum essential medium (MEM), or MEM containing 0.4% albumin. Filtrate and wear debris from extracts were analyzed separately.
The filtrates of Ag-Sn alloy in MEM and MEM containing 0.4% albumin were cytotoxic, while those of the other metallic biomaterials were slightly cytotoxic. Cupper was selectively dissolved from gold and Ag-Pd-Cu-Au alloys, zinc from Ag-Sn and Ag-In alloys, and nickel from Ni-Cr alloy. Titanium was not detected in the filtrate. It was found that dissolution of metallic biomaterials was increased by addition of amino acids and/or albumin. Wear debris of all the metallic biomaterials except titanium was cytotoxic, though cytotoxicity of gold alloy in MEM containing 0.4% albumin was lower. More authentic simulations of in vivo environments are essential to increase the validity of biomaterials test results.

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I purified outer membrane proteins (OMPs) of Porphyromonas gingivalis and examined their immunological activities for leucocytes. The OMPs were purified from P. gingivalis 381. SDS-PAGE analysis revealed that P. gingivalis had two main OMPs of 40 kDa and 53 kDa. Antibodies to both of these proteins have been observed in the sera of patients with adult periodontitis. I found that both had chemotactic activity for human monocytes and both stimulated chemotactic activity for leucocytes in cultures when they were applied to lymphocytes. However, when they were applied to macrophages, chemotactic activity appeared only in the culture stimulated with the 40 kDa OMP.

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The purpose of this study was to investigate the properties of a new device for testing the marginal toughness and wear resistance of dental restorative materials.
The ODU wear test apparatus combined with the new device was used for these experiments. The following experiments were undertaken.
1. An amalgam (Spherical-D : AM), a chemical cure composite resin (Clearfil Posterior : CP) and a glass ionomer cement (Base Cement : BC) were tested to determine the range for this apparatus.
2. Four light cure composite resins such as PhotoClearfil A (PA), PhotoClearfil Bright (PB), Clearfil PhotoPosterior (PP), and Clearfil Composite Inlay (IN) were tested to evaluate the effect of heat treatment on marginal toughness and wear resistance.
3. Two types of wear, at the margin and at the bottom of the sample, were evaluated.
The following results were obtained.
1. The marginal toughness and wear resistance test showed that AM was the strongest, followed by CP and BC.
2. Wider marginal fracture and deeper wear obtained, as the number of loading cycles were increased.
3. AM and CP showed higher marginal toughness as the marginal angle increased. However, BC did not show any correlation between marginal toughness and the marginal angle.
4. AM, CP and BC showed higher wear resistance as the marginal angle increased.
5. Heat treatment significantly improved the marginal toughness of PA, PP and IN. Although the wear resistance of these resins was not improved, the wear resistance of PB was improved significantly. However, its marginal toughness was not improved.
6. PB had the largest difference in the depth of the two types wear, being significantly different from PA, PP and IN.
From these results, it was concluded that this apparatus was capable of evaluating the marginal toughness and wear resistance of restorative materials with physical properties ranging from those of amalgam to glass ionomer cement.

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Penicillin G (PCG) resistant organisms obtained from the saliva of elementary school children were identified and their β-lactamase activities were examined. PCG resistant strains in saliva ranged from 3.0×10² to 6.9×10⁴ CFU/ml. Prevotella, an anaerobic, gram negative rod, predominated, followed by Fusobacterium and Capnocytophaga. Among these, P. melaninogenica was most prevalent. A total of 50% or more of the Prevotella strains produced β-lactamase. These results suggest a need for restraint in administration of β-lactam antibiotics to chidren.

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A new course titled "Data-Processing Practice" was begun in April 1990 for all students in the first year at Osaka Dental University. The goal was to introduce an information processing education into dentistry. New facilities for computer education were constructed for this course at the Hirakata campus. Initial planning included discussions about the distinction between dental and general information and about the future information processing needs of dentists. The aim of the course was to promote the student,s ability to systematically manipulate, consider, and present large quantities of data.

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The course "Data-Processing Practice" at Osaka Dental University consists of (1) lecture on the information society and distinctions between general and dental information, (2) keyboarding, (3) Japanese word-processing, and (4) computer language and algorithm education. Skilled instructors and considerable effort in preparing materials were required. Classroom examinations and student evaluations indicated that the first three goals were achieved and that the students understood the use of and became comfortable with computers. However, the degree of comprehension of computer languages varied widely among the students, indicating the need for further improvements in both teaching skill and materials.

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Infantile behavior development was investigated in the senescence accelerated mouse (SAM)-R/1 and P/8. No differences were found in the physical growth (body weight and time for morphodifferentiation). It was found that there were four stages in the behavioral development when measured by reflexes, locomotive activities, grooming, orienting, tropistic creeping and bar-holding ability. In the fourth stage, athletic exercise-ability in the SAM-P/8 was less than that in the SAM-R/1. This difference was caused by changes in maternal behavior (learning and memory impairments), confirming the importance of the mother. These results indicated that behavioral characteristics in SAM-P/8 begin in infancy.

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I examined the removability, casting porosity, surface hardness, surface microstructures, elemental analysis, and dimensional change of pure titanium cast crowns constructed using a thermal expansion inhibited investment mixed with water which had a colloidal silica solution of 0%, 10%, 20%, 30% or 40%. The commercially available phosphate-bonded investments Titaniumvest and Ceramigold were used as controls. An experimental argon-arc pressure casting machine was used with the casting mold at room temperature. It was found that good, dimensionally accurate, cast titanium crowns could be obtained with the proper colloidal silica solution.

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We studied the formation of radicular granulomas induced by the stimulating factors, LPS, BSA, and KLH-coupled latex beads and plain latex beads. Each factor was either introduced into the mandibular first molar canals or injected into artificial dorsal air pouches in the rats. Periapical lesions and dorsal specimens were histopathologically and immunohistochemically examined. The cells harvested from the exudates in the air-pouches were smeared on glass slides. LPS induced an extensive granuloma pouch. Granulomatous lesions were induced in the periapical regions by KLH-coupled and plain latex beads. These results indicate the possibility of participation of insoluble bacterial factors in periapical granuloma formation.

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