In vitro evaluation of marginal accuracy, load to failure and shear bound strength of pressable ceramics on alumina core
Date
2004
DOI
Authors
Albanna, Anwar Ismail Ebrahim
Version
OA Version
Citation
Abstract
Objectives: To determine the marginal accuracy, load to failure and shear bond strength of an experimental all-ceramic system that combines the use of a milled alumina coping and a pressable ceramic veneer in comparison with conventional porcelain-fused-to-metal (PFM) crowns. Materials and Methods: The test group was composed of In-Ceram alumina (Vita Zahnfabrik, Bad Sackngen, Germany) copings milled by using the Cerec In-Lab CAD-CAM system on which VP7 ceramics (Vita Zahnfabrik, Germany) was pressed. The control group was composed of PFM crowns. The crowns were cemented with Rely-X ARC resin cement (3M/ESPE, St. Paul, Mim.) on epoxy resin dies duplicated from a single prepared typodont tooth (Columbia Dentoform Corporation, Long Island City, N.Y.). Load to failure was tested by placing a ball at the central fossa of the molar crowns. A load was applied on the ball with a universal testing machine (mode1 4202, Instron Corp., Canton, MA). Similarly fabricated crowns were sectioned bucco-lingually and mesio-distally and the marginal, axial and occlusal gaps between the epoxy resin die and the pressed VP7 ceramic material were measured by using a videomicrometer (model JV 6000, Javelin systems, USA). For the shear bond strength test, discs of the coping material were made and rods of the corresponding veneering material were fabricated on the center of 1 of the flat surfaces of the discs. A testing apparatus placed a flat edge at the interface of the coping and veneering material on which a load was applied with a universal testing machine. Results: The VP7-Pressed-to-alumina group had a load to failure of 1374 N [plus or minus] 223N. The PFM group had a load to failure of 1776 N [plus or minus] 319 N, which was significantly greater than that of the PFM crown (p = 0.013). For measurements of marginal gaps, the VP7-pressed-to-alumina group measured 94[mu]m [plus or minus] 36[mu]m, while the PFM group measured 45[mu]m [plus or minus] 16[mu]m. Mean marginal gaps for the VP7 groups (with and without glass control) were significantly greater than those of the PFM group (p [less than] 0.0001). The group that was prepared with a plate of alumina and a rod of pressed ceramics (VP7) had a shear bond strength of 19.9 MPa, [plus or minus] 3.1, while the specimens that had undergone glass control had a shear bond strength of 18.O MPa [plus or minus] 5.9. The PFM group had a shear bond strength of 62.8 MPa [plus or minus] 2.7, which was significantly greater that both of the VP7 group (p = 0.01). Conclusions: The marginal gaps of the PFM crowns with the porcelain butt joints were smaller than the gaps for the VP7-alumina crowns. The VP7-alumina crowns failed in three modes: fracture of the veneer, catastrophic failure through the core, and failure that involved the epoxy die. The mean failure load of all the VP7-alumina crowns combined was significantly less than the PFM crowns. The shear bond strength of PFM crowns was superior to that of the porcelain-pressed-to-glass-infused alumina.
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Thesis (M.S.D.)--Boston University, Henry M. Goldman School of Dental Medicine, 2004 (Prosthodontics).
Includes bibliographical references (leaves 46-49).
Thesis (M.S.D.)--Boston University, Henry M. Goldman School of Dental Medicine, 2004 (Prosthodontics).
Includes bibliographical references (leaves 46-49).
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This work is protected by copyright. Downloading is restricted to the BU community. If you are the author of this work and would like to make it publicly available, please contact open-help@bu.edu.