ラミネートベニア陶材の基礎的研究
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概要
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The porcelain laminate method has been used for esthetic improvement of tetracycline-caused discoloration of anterior teeth or devitalized anterior teeth. However, with this method, the amount of tooth to be trimmed has to minimized, considering the enamel thickness and stimulation of dental pulp. Therefore, the restorative material used with this method has to be very thin, and hence involves a high risk of destruction during manipulation or trial application. To solve this problem, we recently attempted to improve the strength of commercially available laminated veneer porcelains by adding rare earth elements (Sm_2O_3,Eu_2O_3,CeO_2 and La_2O_3) at concentrations of 0.1,0.3,0.5,0.7,1.0 and 1.5%. The physical properties of these laminated veneer porcelains were as follows. Commercial laminated veneer porcelains were chiefly comprised of SiO_2,Al_2O_3 and K_2O. They additionally contained Na_2O, CaO, SnO_2,MgO, ZrO_2,Fe_2O_3 and V_2O_4. In analysis of the grain size distribution of commercially available finished products of laminated veneer porcelain, the median grain size was 15-24μm. In the same analysis for raw materials, the median grain size was 9μm. Thermal expansion was about 0.9% for both raw materials and finished products. The compression strength ranged from 1060 to 1340 MPa for finished products and was 1179 MPa for raw materials. Addition of Sm_2O_3 (0.1%), Eu_2O_3 (0.3%), CeO_2 (0.5%) or La_2O_3 (0.7%) increased the strength of raw materials by 250-350 MPa. Diametrical tensile strength ranged from 32-40 MPa for finished products and was 39 MPa for raw materials. Addition of Sm_2O_3,Eu_2O_3,CeO_2 or La_2O_3 (each 0.5%) increased the strength of raw material by 3-27MPa. X-ray diffraction disclosed a peak of Leucite (K_2O・Al_2O_3・4SiO_2) at about 27° for both finished products and raw materials. Leucite content after sintering did not significantly differ from that before sintering. In color analysis, the degree of transparency of products made of Cosmotech was higher in ascending order of masking dentin, dentin, enamel and translucent, while the b value decreased in this order. The degree of transparency of products made of Pencraft were higher in ascending order of dentin, enamel and translucent.
- 福岡歯科大学学会の論文
- 1991-06-30