Abstract | INTRODUCTION: METHODS: For all materials, the fracture strength, Weibull parameter and elastic moduli were experimentally determined in a four-point-bending test. For the components of the Empress 2 system, the fracture toughness K(IC) was determined, and the crack propagation parameters n and A were determined in a dynamic fatigue method. Using these data, life data analysis was performed and lifetime diagrams were produced. The development of strength under static fatigue conditions was calculated for a period of 5 years. RESULTS: The newly developed veneering ceramic Eris showed a higher fracture strength (sigma(0)=66.1 MPa) at a failure probability of P(F)=63.2%, and crack growth parameters (n=12.9) compared to the veneering ceramic Empress 2 (sigma(0)=60.3 MPa). For Empress 2 veneer the crack propagation parameter n could only be estimated (n=9.5). This is reflected in the prognosis of long-term resistance presented in the SPT diagrams. For all materials investigated, the Weibull parameter m values ( Empress 2 framework m=4.6; Empress 2 veneer m=7.9; Eris m=6.9) were much lower than the minimum demanded by the literature ( m=15). SIGNIFICANCE: The initial fracture strength value alone is not sufficient to characterize the mechanical resistance of ceramic materials, since their stressability is time-dependent. Knowledge about the crack propagation parameters n and A are of great importance when preclinically predicting the clinical suitability of dental ceramic materials. The use of SPT diagrams for lifetime calculation of ceramic materials is a valuable method for comparing different ceramics.
|
Authors | Gergo Mitov, Ulrich Lohbauer, Mohammad Abed Rabbo, Anselm Petschelt, Peter Pospiech |
Journal | Dental materials : official publication of the Academy of Dental Materials
(Dent Mater)
Vol. 24
Issue 2
Pg. 267-73
(Feb 2008)
ISSN: 0109-5641 [Print] England |
PMID | 17631955
(Publication Type: Comparative Study, Journal Article)
|
Chemical References |
- Empress 2
- Eris ceramic
- Lithium Compounds
- Dental Porcelain
|
Topics |
- Algorithms
- Ceramics
(chemistry)
- Dental Porcelain
(chemistry)
- Dental Restoration Failure
- Dental Veneers
- Elasticity
- Hardness
- Humans
- Lithium Compounds
(chemistry)
- Materials Testing
- Pliability
- Probability
- Stress, Mechanical
- Surface Properties
- Time Factors
|