Influence of hydrothermal and mechanical conditions on the strength of zirconia |
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| Authors: | Lothar Borchers Meike Stiesch Friedrich-Wilhelm Bach Josef-Christian Buhl Christoph Hübsch Tim Kellner Philipp Kohorst Michael Jendras |
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| Institution: | 1. Department of Prosthetic Dentistry and Biomedical Materials Science, Hannover Medical School, Carl-Neuberg-Straße 1, 30625 Hannover, Germany;2. Institute of Materials Science, Leibniz Universität Hannover, An der Universität 2, 30823 Garbsen, Germany;3. Institute of Mineralogy, Leibniz Universität Hannover, Callinstraße 3, 30167 Hannover, Germany;1. Analitical Laboratory of Restorative Biomaterials – LABiom-R, School of Dentistry, Federal Fluminense University, Niterói, Rio de Janeiro, Brazil;2. Physics Institute, Federal Fluminense University, Niterói, Rio de Janeiro, Brazil;3. Department of Prosthetic Dentistry, School of Dentistry, Rio de Janeiro State University, Rio de Janeiro, Brazil;4. Department of Dentistry, School of Dentistry, Federal University of Rio Grande do Norte, Rio Grande do Norte, Brazil;1. Dental Science Graduate Program, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil;2. School of Dentistry, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil;3. Department of Restorative Dentistry, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil;1. Research Associate Professor, Department of Material Science and Engineering, University of Washington, Seattle, Wash;2. Professor, Department of Restorative Dentistry, School of Dentistry; Adjunct Professor, Department of Material Science and Engineering, University of Washington, Seattle, Wash;3. Research Assistant, Department of Material Science and Engineering, University of Washington, Seattle, Wash;4. Research Associate Professor, Department of Oral Health Sciences, University of Washington, Seattle, Wash;1. Department of Prosthetic Dentistry/Dental Materials Science, Faculty of Odontology, Göteborg University, Medicinaregatan 12F, Göteborg 405 30, Sweden;2. Laboratory for Redox Regulation, Tohoku University Graduate School of Dentistry, 4-1 Seiryo-machi, Aoba-ku, Sendai 980 8575, Japan;3. Division of Molecular and Regenerative Prosthodontics, Tohoku University Graduate School of Dentistry, 4-1 Seiryo-machi, Aoba-ku, Sendai 980 8575, Japan;4. Tohoku University School of Dental Laboratory Technicians, 4-1 Seiryo-machi, Aoba-ku, Sendai 980 8575, Japan;5. Department of Clinical Dentistry/Faculty of Health Sciences, The Arctic University of Norway, Tromsø 9037, Norway;1. Department of Materials Engineering, KU Leuven, Kasteelpark Arenberg, 44, B-3001 Heverlee, Belgium;2. Electron Microscopy for Materials Science (EMAT), University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium;3. KU Leuven BIOMAT, Department of Oral Health Sciences, KU Leuven & Dentistry, University Hospitals Leuven, Kapucijnenvoer, 7, blok a, B-3000 Leuven, Belgium |
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| Abstract: | Low temperature degradation and mechanical and thermal cycling may decrease the strength of zirconia and jeopardize the long-term success of dental restorations made of this material. The objective of this study was to reveal the influence of different environmental and loading conditions on the strength of 3 mol.% yttria-stabilized polycrystalline tetragonal zirconia (3Y-TZP). A total of 144 disk specimens were produced from each of two 3Y-TZP materials, and subjected to one of the following conditions: (A) no further treatment (control); (B and C) 106 and 5 × 106 mechanical cycles, respectively, with an upper load limit of 100 N; (D) 104 thermal cycles between 5 and 55 °C; (E) 200 days storage in water at 36 °C; (F) a successive combination of conditions B, D and E; (G) storage in water at 80 °C for 64 days; (H) storage in an autoclave at 134 °C for 8 h. Monoclinic phase content was evaluated by X-ray diffraction (XRD) analysis. Specimen strength was determined in a biaxial bending test. The two ceramics exhibited average strengths of 995 and 1239 MPa, respectively. No statistically significant influence of any treatment on strength was demonstrated for either material. However, XRD measurements revealed a substantial increase in monoclinic phase content, from an initial 2% (control) to up to 10%, according to storage conditions. As a consequence of hydrothermal loading a tetragonal to monoclinic phase transformation took place at the surface of the 3Y-TZP materials investigated, but, like thermal and mechanical cycling, this did not lead to significant changes in bulk strength. |
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