Influence of Thickness on Residual Stress Profile in Veneering Ceramic Layered: Measurement by Hole-drilling

摘要

To compare thickness of veneering ceramics dependence of the stress profile in veneering ceramic layered on zirconia and metal frameworks. Cylindrical core materials dentine ceramic specimens whose diameter is 20.0mm, thickness is 0.5mm were made with customized method, and then Upcera zirconia and metal plate were veneered, the thickness of the veneering ceramics respectively were 1.25mm, 1.50mm and 1.75mm, a total of six groups (n=10). An CAD-CAM machine was used for the drilling procedure and residual stress profile of all-ceramic crowns and metal-ceramic crowns was calculated. The mean residual stress of zirconia all-ceramic restorations were: respecitively, 60.15±5.54MPa for 1.25mm thickness of veneering; 53.37±5.12MPa for 1.50mm thickness of veneering; 45.64±4.53MPa for 1.75mm thickness of veneering. The mean residual stress of glass infiltrated alumina all-ceramic restorations were: respectively, 61.32± 5.76MPa for 1.25mm thickness of veneering; 52.45±5.35MPa for 1.50mm thickness of veneering; 45.89±4.26MPa for 1.75mm thickness of veneering. Residual stress profile of all-ceramic restorations was significantly different among specimen groups of Y-TZP and Metal plate (P>0.05). There was also significantly different among specimen groups which had same thickness of the veneering ceramics but not belonged to same frameworks (P<0.01). As the depth increases, the stress gradually increases, reaching the maximum at the interface of MV or CV. The residual stress of frameworks was tensile stress, but the residual stress of veneering porcelain interior was compress. With the veneer porcelain thickness, the residual stress of the interface gradually reduce.