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Numerical modeling of the fracture process in a three-unit all-ceramic fixed partial denture
Umeå University, Faculty of Medicine, Department of Odontology, Dental Materials Science. Umeå University, Faculty of Medicine, Department of Odontology.
Department of Civil and Mining Engineering, Luleå University of Technology, Luleå, Sweden.
Department of Civil and Mining Engineering, Luleå University of Technology, Luleå, Sweden.
Umeå University, Faculty of Medicine, Department of Odontology, Dental Materials Science.
2007 (English)In: Dental Materials, ISSN 0109-5641, E-ISSN 1879-0097, Vol. 23, no 8, 1042-1049 p.Article in journal (Refereed) Published
Abstract [en]

OBJECTIVES: The main objectives were to examine the fracture mechanism and process of a ceramic fixed partial denture (FPD) framework under simulated mechanical loading using a recently developed numerical modeling code, the R-T(2D) code, and also to evaluate the suitability of R-T(2D) code as a tool for this purpose. METHODS: Using the recently developed R-T(2D) code the fracture mechanism and process of a 3U yttria-tetragonal zirconia polycrystal ceramic (Y-TZP) FPD framework was simulated under static loading. In addition, the fracture pattern obtained using the numerical simulation was compared with the fracture pattern obtained in a previous laboratory test. RESULTS: The result revealed that the framework fracture pattern obtained using the numerical simulation agreed with that observed in a previous laboratory test. Quasi-photoelastic stress fringe pattern and acoustic emission showed that the fracture mechanism was tensile failure and that the crack started at the lower boundary of the framework. The fracture process could be followed both in step-by-step and step-in-step. SIGNIFICANCE: Based on the findings in the current study, the R-T(2D) code seems suitable for use as a complement to other tests and clinical observations in studying stress distribution, fracture mechanism and fracture processes in ceramic FPD frameworks.

Place, publisher, year, edition, pages
2007. Vol. 23, no 8, 1042-1049 p.
Keyword [en]
Numerical modeling; Dental ceramic; Fracture; Zirconia; Fixed partial denture
National Category
Biomaterials Science
Identifiers
URN: urn:nbn:se:umu:diva-6508DOI: 10.1016/j.dental.2006.06.039PubMedID: 17109952OAI: oai:DiVA.org:umu-6508DiVA: diva2:146177
Available from: 2008-02-26 Created: 2008-02-26 Last updated: 2017-12-14Bibliographically approved
In thesis
1. On dental ceramics and their fracture: a laboratory and numerical study
Open this publication in new window or tab >>On dental ceramics and their fracture: a laboratory and numerical study
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Background Surface treatments and irregularities in the surfaces may affect the fracture of ceramics. The effects of various treatments on the surface texture of different types of ceramic cores/substructures was therefore qualitatively, quantitatively and numerically evaluated. Since fractures in ceramics are not fully understood, the fracture behavior in dental ceramic core/substructures was also studied using both established laboratory methods and newly developed numerical methods.

Methods The surfaces of dental ceramic cores/substructures were studied qualitatively by means of a fluorescence penetrant method and scanning electron microscopy, quantitatively evaluated using a profilometer and also numerical simulation. In order to study fracture in zirconia-based fixed partial denture (FPD) frameworks, fractographic analysis in combination with fracture tests and newly developed two-dimensional (2D) and three-dimensional (3D) numerical modeling methods were used. In the numerical modeling methods, the heterogeneity within the materials was described by means of the Weibull distribution law. The Mohr–Coulomb failure criterion with tensile strength cut-off was used to judge whether the material was in an elastic or failed state.

Results Manual grinding/polishing could smooth the surfaces on some of the types of dental ceramic cores/substructures studied. Using the fluorescence penetrant method, no cracks/flaws apart from milling grooves could be seen on the surfaces of machined zirconia-based frameworks. Numerical simulations demonstrated that surface grooves affect the fracture of the ceramic bars and the deeper the groove, the sooner the bar fractured. In the laboratory tests the fracture mechanism in the FPD frameworks was identified as tensile failure and irregularities on the ceramic surfaces could act as fracture initiation sites. The numerical modeling codes allowed a better understanding of the fracture mechanism than the laboratory tests; the stress distribution and the fracture process could be reproduced using the mathematical methods of mechanics. Furthermore, a strong correlation was found between the numerical and the laboratory results.

Conclusion Based on the findings in the current thesis, smooth surfaces in areas of concentrated tensile stress would be preferable regarding the survival of ceramic restorations, however, the surfaces of only some of the ceramic cores/substructures could be significantly affected by manual polishing. The newly developed 3D method clearly showed the stress distribution and the fracture process in ceramic FPD frameworks, step by step, and seems to be an appropriate tool for use in the prediction of the fracture process in ceramic FPD frameworks.

Place, publisher, year, edition, pages
Umeå: Umeå universitet, 2010. 53 p.
Series
Umeå University odontological dissertations, ISSN 0345-7532 ; 113
Keyword
Dental ceramics, Finite element analysis, Fixed partial denture, Fracture, Numerical modeling, Surface treatment
National Category
Biomaterials Science
Research subject
Odontology
Identifiers
urn:nbn:se:umu:diva-36590 (URN)978-91-7459-037-1 (ISBN)
Public defence
2010-10-29, Sal 260, byggnad 3A, Norrlands universitetssjukhus, Umeå, 13:00 (Swedish)
Opponent
Supervisors
Available from: 2010-10-08 Created: 2010-10-05 Last updated: 2011-10-11Bibliographically approved

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