カラーレスポーセレン冠の歯肉組織におよぼす影響

Abstract

This study has revealed the effects of collarless metal-ceramic crowns on the dog gingival tissues at one and three months after setting, and compared the effects with those of metal-ceramic crowns by means of light-and scanning electron microscopy. In addition, the morphology of the marginal surface of these two types of crowns was also examined before setting. The results obtained were summarized as follows : 1. It seemed to be necessary to use the correct powder of margin (C.P.M.) for getting a good adapted margin of collarless metal-ceramic crowns made by the non-matrix method. 2. The average thickness of cement layers was 66.2μm in metal-ceramic crowns and 73.2μm in collarless metal-ceramic crowns. 3. Similar inflammatory changes in gingival tissues were observed in both cases of these two crown types by light- and scanning electron microscopy, even when the brushing treatment was performed during experimental periods. 4. Plaque observed in the area of the crown margin had a tendency to accumulate in the boundary between metal collar and porcelain in metal-ceramic crowns, and in the rounded marginal surface in collarless metal-ceramic crowns. 5. When margins of these two types of crowns were observed scanning electron microscopically before setting, a number of pits were found on the surface closely associated with metal collar in case of metal-ceramic crowns. In collarless metal-ceramic crowns, on the other hand, the surface of C.P.M. showed rough appearances. 6. Roughness of C.P.M. surface could be reformed smoothly by reglazing after scraping its superficial layer with sandpaper- or white points.