| 1340 Influence of veneering on the Fracture strength of All-ceramic Bridges | ||
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H.F. KAPPERT1, M. SCHWEIGER2, S. SCHROEDER1, C. WILLE1, and V. RHEINBERGER1, 1Ivoclar Vivadent AG, Schaan Furstentum, Liechtenstein, 2Ivoclar Vivadent, Schaan, Liechtenstein Objectives: The purpose of this study was to determine the in vitro failure load of 3-unit posterior dental-bridges made of lithium-disilicate ceramic (Empress2 and two experimental press ceramics and one for CADCAM processing, all Ivoclar Vivadent) and to compare the data with those of zirconia bridges (DCS, Denzir). Methods: All-ceramic frameworks, veneered frameworks and if applicable anatomically formed posterior bridges were tested with a universal testing machine. Per group 7 specimens were fabricated, in total 105 bridges. For veneering a new universal layering ceramic which matches both lithium-disilicate ceramic and zirconia was used. All frameworks possessed approximately the same dimensions with connectors of 16mm2. The veneered as well as anatomically formed bridges had a total cross section of approximately 30mm2. After cementing the specimens the pontics were loaded until failure. The failure data were analyzed with ANOVA statistics. Results: The fracture strength of the lithium-disilicate frameworks was 540±145N independent of the processing technique. After veneering the fracture strength raised to 752±14N due to the increased total cross sections. The anatomically lithium disilicate bridges reached 960±187N. For Denzir-Zirkon frameworks with 14mm2 cross sections the failure load values ranged 2423±849N, DCS-Zirkon with 16mm2 cross sections reached 3966±612N. After veneering the fracture load dropped significantly to 1745±240N for Denzir-Zircon and to 3107±350N for DCS Zircon. Conclusions: 1. The mechanical strength of the experimental lithium-disilicate ceramic for CADCAM processing is comparable with Empress2 2. Only anatomically formed 3-unit posterior bridges manufactured with lithium-disilicate ceramic fulfill the clinical requirements for posterior bridges considering strength. 3. Veneering frameworks of medium strength ceramic (300MPa) with low strength ceramic (100MPa) increases the strength of the complete restoration in comparison to the framework. 4. Veneering frameworks of high strength ceramic (900MPa) with low strength ceramic (100MPa) decreases the strength of the complete restoration in comparison to the framework. | ||
| Seq #151 - Ceramics: CAD/CAM, Microstructure, and Physical Behavior 9:00 AM-10:30 AM, Friday, 11 March 2005 Baltimore Convention Center 322-323 | ||
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