We investigated the characteristics and mRNA expression of hepatocyte growth factor (HGF) in the adult female monkey submandibular gland using Western blot analysis and the reverse-transcriptase PCR (RT-PCR) technique, and observed HGF mRNA localization using the in situ RT-PCR technique. HGF was extracted with PBS containing protease inhibitors, and purified partially by heparin affinity chromatography. With Western blot analysis, the HGF fraction showed an immunopositive protein band of 69-kDa corresponding to the α-subunit of HGF. The gene expression for HGF was revealed in the monkey submandibular gland using RT-PCR, and the PCR products showed high homology to cDNA for human HGF. Furthermore, the mRNA signal for HGF was localized in the striated and excretory ductal cells. These results unequivocally confirmed both the synthesis and existence of HGF in monkey submandibular glands.(J Osaka Dent Univ 1998；32：37-42）

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Using monoclonal antibodies, we performed immunohistochemical investigations of the expression of α₂, α₃ and β₄ integrin subunits within the squamous epithelial linings of odontogenic cysts. Tissue samples consisted of both follicular cysts and odontogenic keratocysts from 15 patients. It was found that β₄ integrin was expressed on the basement membrane regardless of the histological type of the cyst. The degree of immunostaining for α₂ and α₃ integrin expression corresponded to the thickness of the epithelial cyst wall. We found that the thickness of the epithelial lining of odontogenic cysts had a direct correlation with the expression of integrin molecules.(J Osaka Dent Univ 1998；32：43-46)

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We evaluated the effect of impression materials used in preparation of pure titanium castings on the surface reactive layer. Surface roughness of the refractory models before and after firing was smaller when silicone rather than agar impression material was used. The surface roughness of castings prepared with T-Invest varied little with the impression material. However, the surface roughness of the castings prepared with CD Titaninvest was less when silicone impression material was used. Surface hardness of the castings was slightly greater when agar impression material was used, and metallic texture analysis of the surface of the castings showed a chill layer and a columnar crystal layer extending from the surface toward the interior. A relatively non-corroded white layer and a markedly corroded black layer were observed in the chill layer, and their thickness was smaller when silicone impression material was used.
Use of the Electron Probe Micro Analyzer (EPMA) to determine distribution of various elements in the superficial layer of the casting plates showed that the reactive layer contained less P and Si when silicone impression material was used rather than agar. NH₄H₂ PO₄, which is a component of the bonding material in the investment, was present at a high concentration in the superficial layer of the agar impression material. This shows the importance of preparing refractory models with a non-water-absorbing impression material to obtain pure titanium casting plates with a smaller reactive layer.(J Osaka Dent Univ 1998；32：47-57.)

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Titanium (Ti) is very effective as a dental implant material owing to its low toxicity and high biocompatibility. I carried out in vitro experiments on the adsorption of salivary proteins and serum proteins to Ti to better understand how this material reacts in the oral cavity. I found that when Ti that had adsorbed serum proteins was exposed to salivary proteins, there was an exchange of the proteins on the Ti surface. The same thing happened when Ti that had adsorbed salivary proteins was exposed to serum proteins. These results suggest that both human salivary proteins and serum proteins adsorb to Ti with different affinity, and that protein already adsorbed to Ti might mask binding sites for other proteins.(J Osaka Dent Univ 1998；32：59-65)

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We developed a new type of calcium phosphate cement for clinical use in endodontics as a root canal sealer or pulp cupping agent. The solid phase of the sealer is composed of 70% of α-tricalcium phosphate (α-TCP) and 30% of titanic oxide (TiO₂), and the liquid phase is 37% citric acid, 5% tannic acid and 58% distilled water. TiO₂ was added to control setting time and handling of the cement. We used commercially available calcium phosphate root canal sealer as a control. ISO standards specify that new endodontic products should be examined thoroughly before clinical use. It is important to carry out in vitro cytotoxicity and in vivo histocompatibility tests. We first did in vitro test of setting time and root canal sealing ability of the cement. We found that this developed calcium phosphate cement had an appropriate setting time and excellent sealing ability as a root canal sealer, and concluded that it was suitable for clinical use as a root canal sealer.(J Osaka Dent Univ 1998；32：67-70)

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