Influence of proximal supportive design of zirconia framework on fracture load of veneering porcelain.

The purpose of the present study is to examine the relationship between the supportive designs of proximal region of zirconia framework on the fracture load. The zirconia frameworks with four different supportive designs on the proximal region were fabricated and classified with their radiuses of curvature (R): R=0.5 mm, R=1.0 mm, R=1.5 mm, and R=2.0 mm. The zirconia frameworks were conditioned with sandblast and veneering porcelain was fired. Subsequently, fracture tests were performed at 3 different load points: right above the lowest point of the boundary between veneering porcelain and zirconia framework; 0.5 mm inside from right above point; and 0.5 mm outside from right above point. The fracture load increased with an increase in the radius of curvature of supportive design when loading was applied from above and inside. This suggested that supportive design influenced the fracture load.