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Projects / Programmes source: ARIS

Ageing of dental zirconia (Y-TZP) ceramics under simulated clinical conditions.

Research activity

Code Science Field Subfield
2.04.00  Engineering sciences and technologies  Materials science and technology   

Code Science Field
T153  Technological sciences  Ceramic materials and powders 
Keywords
dental ceramics; Y-TZP; phase transformation; ageing; fatigue;
Evaluation (rules)
source: COBISS
Researchers (8)
no. Code Name and surname Research area Role Period No. of publicationsNo. of publications
1.  11142  PhD Milan Ambrožič  Materials science and technology  Researcher  2008 - 2009  258 
2.  17165  PhD Aleš Dakskobler  Materials science and technology  Researcher  2008 - 2011  153 
3.  17286  Darko Eterović    Technical associate  2010 - 2011 
4.  03477  PhD Tomaž Kosmač  Materials science and technology  Head  2008 - 2011  505 
5.  29548  PhD Sebastjan Perko  Materials science and technology  Junior researcher  2008 - 2011  20 
6.  27778  Natalija Petkovič Habe    Technical associate  2008 - 2011  21 
7.  19990  PhD Irena Pribošič  Materials science and technology  Researcher  2008 - 2009  36 
8.  13550  PhD Krunoslav Vidović  Materials science and technology  Researcher  2009 - 2011  25 
Organisations (1)
no. Code Research organisation City Registration number No. of publicationsNo. of publications
1.  0106  Jožef Stefan Institute  Ljubljana  5051606000  91,059 
Abstract
In the past decade there have been major advances in the application of yttria partially stabilized zirconia (Y-TZP) ceramics for dental restorations; this is due to the improved aesthetics, excellent tissue compatibility and superior mechanical properties compared to other dental ceramics. Under clinical conditions, all-ceramic dental restorations are exposed to mechanical fatigue and thermocycling in an aggressive saliva environment in the oral cavity, leading to stress corrosion. Furthermore, due the metastability of tetragonal zirconia, Y-TZP ceramics are prone to ageing in the presence of water, which may ultimately lead to strength degradation. The phenomenon is well known and documented, but still not completely understood. In this project, we propose to investigate the ageing behaviour of conventionally sintered bio-medical grade 3Y-TZP ceramics for dental applications under simulated clinical conditions. Materials differing in their mean grain size, transformability, inherent strength and fracture toughness will be produced and subjected to standard dental grinding and sandblasting procedures prior to thermal and mechanical cycling in an artificial saliva solution. The propagation of the tetragonal-to monoclinic phase transformation will be monitored and equations describing the transformation kinetics will be established. The effects of mechanical surface treatments and accelerated aging under non-isothermal conditions on the biaxial flexural strength and fatigue behaviour will be determined and statistically evaluated. It is expected that the results gathered during the course of this project will contribute to further improvement of Y-TZP dental ceramics and pave the way for a reliable in-vivo lifetime prediction of Y-TZP-based dental restorations. Results will also be used in practice: in collaboration with an industrial partner, a pilot-plant production line will be established for manufacturing biscuit-sintered Y-TZP blanks for CAD/CAM fabrication of prosthetic dental crowns and bridges.
Significance for science
Ageing of Y-TZP ceramics under clinical conditions is considered to be a very complex problem that is not yet well understood. The conducted research is up-to-date as the zirconia market for dental application is growing ever greater, but no such systematic investigation has been performed so far. A contribution to a more fundamental understanding of the mechanisms and kinetics is expected to be well received in the scientific community.
Significance for the country
The research of dental ceramics supports areas, which are especially perspective for Slovenia, since it enables increase in scientific knowledge and scientific and technological competitiveness based on the values of human society according to European priorities (National R&D program 2006 to 2010), in particular advanced artificial metal and non-metallic materials and nanotechnologies and Complex Systems and innovative technologies. The project fits into the third priority of the tender (research of new materials, new production technologies). The industrial partner of the proposed research is Interdent company from Celje, which produces and markets dental materials and auxiliary products for dental laboratories. The company is currently establishing a new production plant for manufacturing of biscuit-sintered zirconia blanks used in CAD/CAM milling of dental prosthetic cores. The results of the project will help the industiral partner in the selection of the raw materials, as well as in proper adjustment of the key- technological parameters necessary to assure a reproducible production of reliable FPDs. These are considered as high performance and high added-value products. The results of our work will thus be implemented into practice which, in turn, will lead to new opening positions for highly specialized engineers and technicians in a less developed part of the country. During the course of the project an intensive cooperation and tight links havel been established between industry and researchers at the Institute. The project also contributes to education of young researchers. Two of the researchers from the project team are university professors and are giving courses in physics, ceramic engineering and bio-materials at the University of Ljubljana and Jožef Stefan International postgraduate school. Principal Investigator was mentor to two PhD students at Medical Faculty (in the field of dental ceramics).
Most important scientific results Annual report 2008, 2009, final report, complete report on dLib.si
Most important socioeconomically and culturally relevant results Annual report 2008, 2009, final report, complete report on dLib.si
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