Carlos Eduardo Edwards Rezende1, Ana Flávia Sanches Borges2, Carla Castiglia Gonzaga3, Yuanyuan Duan4, José Henrique Rubo5, Jason Alan Griggs6. 1. Department of Prosthodontics, Bauru School of Dentistry, University of São Paulo, Alameda Octávio Pinheiro Brisolla 9-75, Bauru, SP 17012-901, Brazil; Post-Graduation Program in Clinical Dentistry, Dental School, Positivo University, 5300 Pedro Viriato Parigot de Souza Rd., Curitiba, PR 81280-330, Brazil. Electronic address: caerezende@gmail.com. 2. Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Alameda Octávio Pinheiro Brisolla 7-35, Bauru, SP 17012-901, Brazil. Electronic address: afborges@fob.usp.br. 3. Post-Graduation Program in Clinical Dentistry, Dental School, Positivo University, 5300 Pedro Viriato Parigot de Souza Rd., Curitiba, PR 81280-330, Brazil. Electronic address: carlacgonzaga2@gmail.com. 4. Department of Biomedical Materials Science, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216-4505, USA. Electronic address: yduan@umc.edu. 5. Department of Prosthodontics, Bauru School of Dentistry, University of São Paulo, Alameda Octávio Pinheiro Brisolla 9-75, Bauru, SP 17012-901, Brazil. Electronic address: jrubo@fob.usp.br. 6. Department of Biomedical Materials Science, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216-4505, USA. Electronic address: jgriggs@umc.edu.
Abstract
OBJECTIVE: To evaluate the stress distribution in bi-layered Y-TZP based crowns, according to the occlusal internal spacing between coping and abutment. METHODS: Twelve premolar shaped Y-TZP copings were made by a CAD/CAM system and seated on an abutment to evaluate the internal fit at the occlusal third using micro-CT images. Considering the fitting range obtained experimentally, two 3D finite element models, consisting on bone tissue, a titanium implant, a zirconia abutment, cement layer and a bi-layered Y-TZP ceramic crown were constructed based on the micro-CT images, one corresponding to the thinnest cement space and other representing the specimen with the thickest cement space obtained experimentally. A 250N axial load was applied at the center of the occlusal surface of the crown (≅0,8mm2 area) and the first principal stress distribution was plotted and analyzed. RESULTS: The greatest maximum principal stress occurred within the veneer ceramic right below the site of loading. The thickest cement model showed higher stress concentration at the center of occlusal surface of veneer and the center of occlusal internal surface of coping. SIGNIFICANCE: Knowledge of stress distribution in ceramic crowns with different cement thicknesses will help clinicians to properly adjust crown fit, in seeking to avoid porcelain fractures.
OBJECTIVE: To evaluate the stress distribution in bi-layered Y-TZP based crowns, according to the occlusal internal spacing between coping and abutment. METHODS: Twelve premolar shaped Y-TZP copings were made by a CAD/CAM system and seated on an abutment to evaluate the internal fit at the occlusal third using micro-CT images. Considering the fitting range obtained experimentally, two 3D finite element models, consisting on bone tissue, a titanium implant, a zirconia abutment, cement layer and a bi-layered Y-TZP ceramic crown were constructed based on the micro-CT images, one corresponding to the thinnest cement space and other representing the specimen with the thickest cement space obtained experimentally. A 250N axial load was applied at the center of the occlusal surface of the crown (≅0,8mm2 area) and the first principal stress distribution was plotted and analyzed. RESULTS: The greatest maximum principal stress occurred within the veneer ceramic right below the site of loading. The thickest cement model showed higher stress concentration at the center of occlusal surface of veneer and the center of occlusal internal surface of coping. SIGNIFICANCE: Knowledge of stress distribution in ceramic crowns with different cement thicknesses will help clinicians to properly adjust crown fit, in seeking to avoid porcelain fractures.
Authors: Maximiliane Amelie Schlenz; Jonas Vogler; Alexander Schmidt; Peter Rehmann; Bernd Wöstmann Journal: Int J Environ Res Public Health Date: 2020-03-25 Impact factor: 3.390