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ISO 4049 versus NIST 4877: Influence of stress configuration on the outcome of a three-point bending test in resin-based dental materials and interrelation between standards.

Authors
  • Ilie, Nicoleta1
  • 1 Department of Conservative Dentistry and Periodontology, University Hospital, LMU Munich, Goethestr. 70, D-80336, Munich, Germany. Electronic address: [email protected] , (Germany)
Type
Published Article
Journal
Journal of dentistry
Publication Date
Apr 30, 2021
Volume
110
Pages
103682–103682
Identifiers
DOI: 10.1016/j.jdent.2021.103682
PMID: 33933556
Source
Medline
Keywords
Language
English
License
Unknown

Abstract

The study aimed to find a relationship between the most common standards used in testing resin-based materials (RBC) in a three-point bend test - ISO 4049 and NIST 4877 - using a size-strength relationship defined by the Weibull model. The direct comparison of calculated and measured data is used for validation. 280 (n = 20) specimens were prepared from seven different light-cured RBCs. The flexural strength, FS, and modulus, E, were measured with a span of 12 mm (NIST) or 20 mm (ISO). A fractographic analysis determined the origin of fracture. One and multiple-way analysis of variance (ANOVA), the Tukey honestly significant difference (HSD) post-hoc tests (α = 0.05), Weibull statistics and Pearson correlation analysis were used for data analysis. Calculated data approximate the measured data very well. FS measured according to ISO is 11 % lower and E is 17 % higher than the NIST data. The test method influenced the properties measured, but not the material ranking or the fracture mode. Fractures originated from volume defects (sub-surface) were the most common type of fracture. Weibull analysis is successful to predict the scaling of strengths to other configurations in RBCs. The need to limit the sample size of RBCs up to the dimensions of their clinical use can benefit from the use of Weibull statistics. Weibull size-strength relationship and fractographic analysis can help to better assess the clinical behaviour of the RBCs, calculate the reliability of a restoration, and assess the nature of the flaws in the material. Copyright © 2021 Elsevier Ltd. All rights reserved.

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