We performed a computer analysis of the pulpal threshold of pain predicted for thermal stimuli (heat and cold) using the finite element method. The correlation of pulpal pain was studied in the mandibular first and second primary molars for various restorative materials for application of thermal stimuli to the restorative material and tooth, with changes in cavity preparation form (Class I and Class II) and thermal conductivity of the restorative material.
Our computer simulation showed that heat stimuli applied to the occlusal surface produced pain about 57℃ and cold stimuli at about 21℃. The pain occurred near the pulp horn. We found that for thermal stimuli, restorative materials with lower thermal conductivity induced less pulpal pain. This was true for both Class I and Class II restorations. We also found that there was more pain to thermal stimuli for deeper proximal restorations when the restorative material was of higher thermal conductivity.

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Cisplatin (CDDP) is an extremely active anti-tumor agent, although it has renal and upper GI toxicity. cis-1, 1-Cyclobutanedicarboxylato (2R)-2-methyl-1, 4-butanediamine platinum (II) (NK-121) is a new analogue of CDDP developed for better anti-tumor activity and reduced toxicity. Though it has been reported that NK-121 has less renal toxcity, myelotoxicity is often observed. I studied the anti-tumor activity and toxicity of NK-121 on KB cells subcutaneously transplanted in nude mice. The synergistic effects of the combined chemotherapy of NK-121 and peplomycin (PEP) were also evaluated.
NK-121 showed good anti-tumor activity without significant weight loss or a severe decrease in the number of blood cells.
Combined treatment of NK-121 and PEP was superior to NK-121 alone in its anti-tumor effect. Body weight loss with the combined treatment was slightly less than with therapy of NK-121 alone at the same anti-tumor activity. Combined use of NK-121 and PEP had superior anti-tumor effect to the use of the drugs alone. Also, the combined use did not have significant toxicity.

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Ceramic materials are widely used for restoration of the permanent dentition because of their biocompatibility and aesthetics. I evaluated whether castable ceramics could be applied in clinical pedodontic practice. Wear tests were used to compare several restorative materials, including castable ceramics, and deciduous teeth. Compressive fatigue tests were carried out to evaluate the effect of repeated compressive loads.
I found that the wear volume of castable ceramics was closer to that of deciduous teeth than the other materials. The compressive fatigue strength of castable ceramics was greater than the maximum occlusal force children could produce even after 1,000,000 repeated compressive loads

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I examined the relationship between histological and microvascular changes in the parotid gland and pancreas of streptozotocin-induced diabetic rats in relation to the progression of diabetic microangiopathy. These changes were investigated under light microscopy and scanning electron microscopy of microvascular castings made by the plastic injection method (Ohta et al., 1990).
The microvascular architecture of the parotid gland acinar capillary network appeared normal one week after induction of diabetes. Six weeks after induction the network became coarse, while the network supplying the interlobular duct also gradually became coarse at 16 weeks. One week after induction of diabetes the islet capillary network of the pancreas rapidly became atrophic and by 16 weeks completely disappeared. The acinar capillary network of the pancreas became coarse, although there was no change in the network supplying the ductual system.
In conclusion, histological damage and diabetic microangiopathy occurred in the effected rats : first in the endocrine pancreas, then parotid gland, and lasty in the exocrine pancreas.
In spite of their common histological structure, different organs presented different reactions to insulin dependence.

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Hemisection was performed on the mesial root of a mandibular first molar because of an apical lesion which would not heal after repeated root canal treatment.
The lost mesial portion of the crown was restored by a bridge with the anterior abutment on the second premolar being a parallel pin retained onlay and the distal portion of the first molar being a full crown.

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Conditions of dynamic extraction for cytotoxicity evaluation of metallic biomaterials were studied. A cylindrical shape was better than a plate or sphere in assessing the cytotoxicity of base metals. In addition, a gyration speed of 240rpm and an extraction duration of 5days were superior to 160 or 200rpm, and 3, 7 or 14days, respectively. These conditions are appropriate for examining the cytotoxicity of such base metals as titanium, cobalt chromium and nickel chromium alloys for use as biomaterials.

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Three monoclonal antibodies (MoAbs) NG3, NZ9, and Z17 were produced from electric cell fusion of mouse myeloma cell line NS-1 with spleen cells from BALB/c mice that had been immunized with transplanted squamous cell carcinoma (SCC) from nude mice (TSG1, TSZ2) or immunized with a control tongue tumor. By immunohistochemistry, NG3 (IgM, ^K-chain) and NZ9 (IgG1, ^K-chain) showed strong immunoreaction with the cellular cytoplasm and membrane of moderately and well differentiated SCC, respectively. Z17 (IgM, ^K-chain) strongly immunostained the cellular cytoplasms of poorly differentiated SCC. However, none of the three MoAbs stained the stroma. NG3, NZ9 and Z17 were useful in diagnosing SCC, and in classifying its differentiation.

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Streptococcal strains carrying fibrous structures isolated from the tongue dorsum were identified and their hemagglutination and hydrophobic characteristics were examined. Morphologically different types of fibrils or 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 the streptococci differed from strain to strain. In more than half of the strains, 50% or less of the cells remained in the water phase after agitation with hexadecane. No correlation was found between the types of fibrils or fimbriae, hemagglutination and hydrophobicity, indicating that multilpe factors may exist in the adherence of oral streptococci as early colonizers.

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Penicillin G (PCG) resistant organisms screened from saliva of school age children were identified and their β-lactamase activities were examined. PCG resistant strains in saliva ranged from 3.5×10^2 to 8.7×10^4 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 administering β-lactam antibiotics to children.

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Investigations were made on the changes with experimental malocclusion in the microvascular architecture of the temporomandibular joint disks of Japanese monkeys. All maxillary posterior teeth were extracted and the occlusal surfaces of all mandibular posterior teeth were reduced. The animals were sacrificed at 4, 8, 16 and 24 weeks. Microcasts prepared by injection of acryl plastic were coated with gold for electron microscopic observation. Initially, the distribution of blood capillaries decreased in the posterior portion of the disk while increasing somewhat in the anterior region. However, in time the disk tissue gradually returned to normal.

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Utilizing the acryl plastic injection method, we investigated the blood supply of the lion masseter muscle based on the laminar formation of this muscle as reported by Takemura at al. (1991). Nutrient arterial branches were supplied mainly by the superficial temporal, buccal, facial, masseteric and the posterior auricular arteries, and occasionally by the maxillary and external carotid arteries. Although the superficial temporal in the cat is distributed only to the superficial and intermediate layers of the masseter, it also supplies the deep layer in the lion.

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Utilizing the acryl plastic injection method, we investigated the blood supply of the upper teeth of the crab-eating monkey with particular emphasis on the arterial routes entering the dental pulp. The superior dental rami diverged from the posterior superior alveolar, major palatine, infraorbital, descending palatine and sphenopalatine arteries. The posterior superior alveolar artery supplied the six teeth from M_3 to C. The major palatine supplied the incisors, premolars and rarely M_1. The infraorbital supplied the canine independently or together with the posterior superior alveolar. The descending palatine and sphenopalatine gave off molar branches entering the palatal roots of the molars.

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Electromyograms of the superior (SLpt) and inferior (ILpt) heads of the lateral pterygoid muscle were recorded and analysed during mastication, together with the condylar and incisal movements. The SLpt appears to have two phasic functions. In the first phase it controls the position and speed of the disc and condyle as it returns posteriorly to centric position. In the second phase, it functions mainly during the final closing phase on the working side to direct the orientation of masticatory forces toward the articular eminence in response to increases in these forces. These functions are completed by the supplementary activity of the ILpt.

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I electromyographically elucidated the reflexes of the inferior head of the human lateral pterygoid muscle, and compared them with those of the masseter muscle and anterior belly of the digastric muscle. Simul-taneous unilateral recordings were obtained for each muscle during electric gingival stimulation and mechanical tapping of the chin. The results suggest that there is an intricate reflex by which the human lateral pterygoid muscle responds to external stimulation for various conditions of voluntary muscle contraction, and that this muscle has a monosynaptic reflex are originating in its muscle spindles.

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