The purpose of this study was to establish the criteria for oral epithelial dysplasia (OED). A total of fifty-six biopsies of white lesions in the buccal mucosa and gingiva were classified into Type I, II and III, and their relationship to expression of PCNA or p53 and keratinization patterns were examined. The appearance of PCNA positive cells coincided with severe atypia in the basal layer. p53 expression revealed focal, diffuse and basal layer patterns. The focal pattern was found in only Type I; both the diffuse and basal layer patterns were seen in Type II. All the cases of Type III showed the basal layer pattern. It is suggested that p53 expression of the basal layer pattern is useful for estimating the malignant potency. Parakeratosis demonstrating a tendency toward severe atypism and general disturbance is an important malignant sign.

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Bones and teeth provide a continuous record of past exposure. They are also a potential reservoir of fluoride. For example, local release of fluoride from the skeletal tissue may increase fluoride concentrations in the immediately adjacent soft tissues. This study compares the fluoride distributions in trabecular (cancellous) bone in relation to periosteal cortical and endosteal cortical bone in human ribs obtained from 40 subjects (male: 26, female: 14) aged 21 to 76 years old. The fluoride concentrations in specimens were determined from abraded samples with a fluoride electrode. Fluoride concentrations were high at the surface and low at the middle of trabecular bone. Fluoride concentrations in periosteal cortical and endosteal cortical bone started to increase at the age of 40-50 in males and 50-60 in females. However the fluoride concentrations in trabecular bone stayed at a low level, but increased after the age of 70 in both male and female subjects. Fluoride profiles in trabecular bone surfaces were similar to those of endosteal cortical bone. It was concluded that fluoride concentrations in trabecular bone, as well as in periosteal cortical and endosteal cortical bone, were affected by conditions of modelling and remodelling.

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We immunohistologically examined the cell densities and distribution of T and B cells in periodontitis and analyzed their relationship in terms of periodontal tissue destruction. Specimens were labeled with monoclonal antibodies for T cells (CD3) and B cells (CD20) and developed using the double staining technique. CD3⁺ cells appeared in low density infiltrates and increased gradually with the number of total infiltrates; in contrast, CD20⁺ cells did not appear in small infiltrates but increased rapidly with the number of infiltrates. The number of fibroblastic cells negatively correlated with that of the total infiltrates and CD20⁺ cells, but it did not correlate with the number of CD3⁺ cells. These findings suggest that the T cells infiltrated into the inflamed sites at the onset and increased gradually with the development of inflammation and that B cells infiltrated later than T cells and their number increased rapidly with inflammation.

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To evaluate the suitability of a new implant animal model, we examined the host response to single crystal sapphire implant into the rat maxilla socket and characterized the regenerating tissue-implant interface using a combination of morphological and immunocytochemical approaches. At 2, 4, and 8 weeks after implantation, animals were sacrificed and tissues processed for morphological or immunocytochemical studies. Results demonstrated that nonmineralized connective tissue was present between bone and the implant surface. However, in some situations at 8 weeks, direct bone contact was observed. Electron microscopy revealed that the interface between the implant and the regenerating tissues was characterized by the presence of either cells or an intervening extracellular matrix layer that had a variable appearance and thickness.The bone-implant interface was immunoreactive for osteopontin. The rat maxilla socket implant model, due to its ease of management and its similarities to other previous experimental animal models, seems to be useful for some specific implant experimental studies.

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The fluoride concentration in the bone of the non-fluoridated female rats increased slowly with age. Up to the age of 12 weeks, the fluoride distribution across the cortical bone was low and showed non-variation from the periosteal region to the endosteal region. From 24 weeks, however, the fluoride concentration in the periosteal and endosteal regions was a little higher than that of the middle region of the cortex. The fluoride concentrations in the bone of the female rats using water containing 100 ppm fluoride increased markedly with age. Six-week old rats showed increased fluoride concentrations in the endosteal region. At 24 weeks, both the periosteal and endosteal regions were higher than the middle region. At 48 weeks, the fluoride concentration in the periosteal region was significantly higher than that of the endosteal region. In conclusion, in younger rats (4, 6, 12, 24 weeks old), the fluoride concentration was lower in the periosteal than in the endosteal region, whereas in older (48 weeks old) rats, the fluoride concentration was higher in the periosteal than in the endosteal region. There were some-what different findings from those on the rat molar cementum in which fluoride was mainly taken up from the cementum surface.

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Basal cell adenocarcinoma is a relatively recently described rare type of malignant salivary gland tumor found most often in the parotid gland. We present a case report of minor salivary gland basal cell adenocarcinoma arising in the mandible. Histologically, tumor islands composed of epithelial cells with two morphologic forms and mitotic figures were frequently observed,and tumor cells invaded alveolar bone. Ultrastructurally, tumor cells had secretory granules, mitochondria desmosomes, tonofilament bundle, and basement membrane. Immunohistochemically, the tumor cells showed positive-immunoreactivities with S-100 protein, CEA, EMA, and keratin.

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A case of polymorphous low grade adenocarcinoma (PLGAC)of minor salivary gland in the oral floor, an extremely rare location for PLGAC, is reported. The histopathology of in this case was characterized by cytological uniformity in a variety of morphological growth patterns, including tubular, solid, trabecular, papillary-cystic, and single file areas. Immunohistochemically, most of the tumor cells were positive for keratin, vimentin, and S-100 protein. Some tumor cells were positive and variably immunoreactive for muscle actin, epithelial membrane antigen(EMA), and carcinoembryonic antigen (CEA). The number of argyrophilic nucleolar organizer regions(AgNOR) is considered to be a reflection of the tumor proliferation rate. The numbers of AgNOR per nucleus in the tubular, solid, and papillary-cystic morphological growth patterns were 1.80 ± 0.08, 1.87 ± 0.04, and 1.78 ± 0.03, respectively. There was no correlation between the number of AgNOR and the growth pattern.

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A carcinoma in pleomorphic adenoma occurring in the tongue of a 47-year-old Japanese woman is reported. The present report is the first to describe a carcinoma in pleomorphic adenoma derived from the posterior lingual glands.

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Salivary duct carcinoma (SDC) is an extremely rare neoplasm which occurs in the salivary gland. We report a case of SDC arising from the parotid gland in an 82-year-old Japanese male. We examined the immunohistochemical studies and surveyed the Japanese cases. We excluded cases which were diagnosed on the basis of the previous classification. The patient underwent a radical parotidectomy. Histopathologically, the tumor exhibited comedo-carcinoma, with infiltrative desmoplasmic and cribriform patterns, and a neural invasion. Immunohistochemical studies demonstrated an SDC which consisted of ductal cells without any participation of myoepithelial cells. We confirmed 24 Japanese cases of SDC, including the present case, by the current WHO classification.

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A case of leiomyosarcoma of the maxillary alveolus in a 45-year old Japanese woman, including ultrastructural and immunohistochemical findings, is reported. The patient was clinically free of tumor 56 months later. By electron microscopic study, the tumor cells contained microfilaments with focal densities and pinocytotic vesicles on the basement membrane. Immunohistologically, the cytoplasm of tumor cells strongly immunoreacted with desmin, vimentin and α-smooth muscle actin, but not with myosin, neurofilament or S-100 protein.

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