Fracture Toughness Testing of Dental Restoratives: a Critical Evaluation
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Purpose of Review
We intend by this short critical review to highlight important aspects regarding the mechanical testing of fracture toughness. The final aim is to increase the awareness to the test sensitivity, ultimately increasing the quality and reliability of reported testing results.
In a well-intended attempt to facilitate testing procedures or provide alternatives for testing material interfaces, authors are resorting to adaptation of testing methodologies without proper theoretical and experimental validation. The assumption of validity in such cases endangers the perpetration of testing strategies that are not safeguarded by sound theoretical bases. The use of improper statistical treatments based on extreme-value distributions further aggravates this scenario.
We supply here some directions for authors concerning method selection, interpretation of data scatter, statistical treatment, and possibilities for test validation.
KeywordsDental restorative materials Mechanical properties Fracture toughness Testing
Compliance with Ethical Standards
Conflict of Interest
The authors declare that they have no conflict of interest.
Human and Animal Rights and Informed Consent
This article does not contain any studies with human or animal subjects performed by any of the authors.
Papers of particular interest, published recently, have been highlighted as: • Of importance •• Of major Importance
- 5.Baratta FI, Matthews WT, Quinn GD. Errors associated with flexure testing of brittle materials. Report no MTL TR 87 - 35, US Army Materials Technology Laboratory. 1987.Google Scholar
- 10.• Wendler M, Valladares M, Petschelt A, Belli R, Lohbauer U. Chairside CAD/CAM materials. Part 3: Cyclic fatigue parameters and lifetime predictions. Dent Mater. In Press. https://doi.org/10.1016/j.dental.2018.03.24. Here, we show how a threshold fatigue parameter derived from the fracture toughness might correlate better to clinical fracture rates than typical parameters based on strength degradation.
- 16.• Belli R, Wendler M, Zorzin JI, Lohbauer U. Practical and theoretical considerations on the fracture toughness testing of dental restorative materials. Dent Mater. 2018;34(1):97–119. Here, we go into details of factors affecting fracture toughness tests and possibilities for dental materials.CrossRefPubMedGoogle Scholar
- 35.•• Mai Y, Lawn BR. Crack-interface grain bridging as a fracture resistance mechanism in ceramics: II. Theoretical fracture mechanics model. J Am Ceram Soc. 1987;70:289. Here, Mai and Lawn established the role of friction between a particulate and the material its embedded in in the toughening through bridging elements.CrossRefGoogle Scholar
- 38.Fett T. New contributions to R-curves and bridging stresses—applications of weight functions. Karlsruhe: KIT Scientific Publisching, Karlsruhe; 2012.Google Scholar