Stress Analytic Study on Fractural Strength and Abutment Form of All Ceramic Crown

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In order to reveal the relation between fracture strength and abutment form of all ceramic crown, we performed fracture test and 3D-FEA of all ceramic crown. In fracture test we used extracted human maxillar incisors as abutment teeth because extraordinary strength were observed in fracture test using metal abutment. 3D-FEA was executed as contact analysis which was introduced by us previously. In contact analysis, the boundaries between materials were not fixed, and results of contact analysis showed good agree with actual fracture of all ceramic crown. Correlation analyses between fracture strength and measurements of abutment were performed. Results of correlation analyses were compared with results of 3D-FEA.In the correlation analyses, strong negative correlation was observed between fracture strength and height of marginal curvature, and strong positive correlation was observed between fracture strength and labial-lingual thickness of all ceramic crown. These results fitted in well with that of 3D-FEA.In 3D-FEA, concentration of tensile stress are observed at the margin of all ceramic crown, and the tensile stress became higher when marginal curvature became higher. When labial-lingual thickness of all ceramic crown became thick, the tensile stress at margin lowered.In case of high marginal curvature, stretching force were generated by tilting displacement toward labial direction, and in case of thick crowns, the displacement became smaller. These strongly seemed to be related to flexibility of abutment.