陶材焼付貴金属冠の歯肉におよぼす影響に関する実験的研究

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To clarify possible reasons of discoloration and recesson of the gingiva upon application of porcelain-fused-to precious metal crown, changes in the metal surface caused by heat treatment or firing as well as changes before and after immersion in an etching fluid of the porcelain-fused-to precious metal crown were analyzed by erectron-probe microanalyses. Furthermore, through vital tissue reactions using test animals and upon application tests of the porcelain-fused-to precious metal crown, influences on the gingiva were studied by histological observations and erectron-probe microanalyses. The results obtained are as follows : 1. Upon heat treatment a coarse oxide layer of tin (Sn) and indium (In) was formed on the metal surface. Upon microscopical observations it was found that microparticles consisting of precious metal components were solid dissolved on the surface of the oxide layer and Sn and In are segregated around grain boundaries and polish scratches. 2. Regardless of covering with fused porcelain, the oxide layer appeared on the metal surface by firing as seen in the case of heat-treated samples. Microparticles observed in heat treatment fused together on the surface and Sn and In were deposited mainly in grooves between those fused microparticles and the part jointed to porcelain. Furthermore, it was also known that the oxide layer was eliminated by polishing, thus segregation of the respective element disappeared. 3. The immersion test in an etching fluid revealed no change on the surface structure of polished specimes, however, heat-treated specimens showed reduction of Sn and In, the oxide layer being fallen off from the surface. Also, microparticles isolated on the surface were observed to be smallar in size and less in quantity. 4. The tissue reaction test using rabbit revealed that fine deposits were seen on connective tissue just below fibroserous membrane covering the heat-treated specimens, and around such deposits granulation tissue mainly consisting of histiocytes and eosinocytes was formed. Upon x-ray microanalyses the deposits proved to be oxides of Sn and In. In addition, from a part of the deposits gold (Au) was detected. 5. Upon crown application test using monkey, dull purple discoloration was recognized on cervical margin of the gingiva in contact with crown, and fine dark brown deposits were found in connective tissue around the blood vessels, fibroblasts, as well as in intravascular endothelia. Upon x-ray analyses the deposits were confirmed to be oxidized Sn and In.
1981-11-25

著者

鬼塚雅
鹿児島大学大学院医歯学総合研究科咬合機能補綴学分野

陶材焼付貴金属冠の歯肉におよぼす影響に関する実験的研究

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