The effect of veneering technique on the failure load of In-Ceram YZ zirconia based all-ceramic crowns
Khiblil, Ali Mohamad M Ahmad
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Statement of the problem: Zirconia based bi-layered restorations can be affected by the strength and homogeneity of the structure of the weakest part (the veneering porcelain). The combination of a CAD/CAM-fabricated framework with CAD/CAM-fabricated veneering would be of major interest to improve the strength and fracture resistance of all-ceramic restorations, especially if stronger veneering ceramics can be applied. However, to date in most cases, veneering material is hand layered. Objectives: To evaluate the failure load of zirconia based all-ceramic crowns veneered with a CAD/CAM generated high-strength veneering porcelain. Interfacial bonding methods included two different cements and fusion porcelain; Compare the bond strength of CAD/CAM based all-ceramic crown systems to crowns fabricated by traditional hand layering technique. Evaluate the effect of thermocycling on the failure load of these crowns and evaluate their failure modes. Materials and Methods: Standardized acrylic dies with 2 mm, 360 degree shoulder preparations (Pober Industries, Waban, MA, USA) were used in this in-vitro study. 48 zirconia copings were produced and divided into eight groups. In the first and second groups (cemented, and cemented + themocycled, n=6 each) CAD/CAM fabricated high-strength anatomically shaped porcelain veneers (VITA VM9) were cemented onto zirconia copings using conventional cement (Rely X Luting GI). In the third and fourth groups (bonded, and bonded + thermocycled, n=6 each) CAD/CAM fabricated porcelain veneers (VITA VM9) were bonded to zirconia copings using resin cement (Multilink Automix). In the fifth and sixth groups (sintered, and sintered + thermocycled, n=6 each) CAD/CAM-fabricated porcelain veneers (VITA VM9) were fused to the zirconia copings using fusion porcelain (VITA VM9). In the seventh and eighth groups (hand layered, and hand layered + thermocycled, n=6 each) zirconia copings received conventional veneering using a layering technique with VITA VM9 porcelain. All crowns were conventionally cemented onto their dies using resin cement. Half the groups were tested directly in a universal testing machine until failure and the other half were thermal cycled and then tested. The fracture load data were compared by a one-way analysis of variance and a multiple comparison posthoc test (alpha=0.05). [TRUNCATED]
PLEASE NOTE: This work is protected by copyright. Downloading is restricted to the BU community: please click Download and log in with a valid BU account to access. If you are the author of this work and would like to make it publicly available, please contact email@example.com.Thesis (MSD) --Boston University, Henry M. Goldman School of Dental Medicine, 2012 (Department of Restorative Sciences and Biomaterials).Includes bibliographic references: leaves 122-127.
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