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Materials (Basel). 2016 Mar 9;9(3). pii: E180. doi: 10.3390/ma9030180.

Influence of Specimen Preparation and Test Methods on the Flexural Strength Results of Monolithic Zirconia Materials.

Author information

1
Department of Prosthodontics, Dental School, Ludwig-Maximilians-University Munich, Goethestrasse 70, Munich 80336, Germany. c.sa.schatz@googlemail.com.
2
Faculty of Engineering and Computer Science, Material Science and Analysis, University of Applied Sciences, Hochschule Osnabrück, Albrechtstrasse 30, Osnabrück 49076, Germany. monika.strickstrock@hs-osnabrueck.de.
3
Department of Biostatistics, Epidemiology Biostatistics and Prevention Institute, University of Zurich, Hirschengraben 84, Zurich 8001, Switzerland. malgorzata.roos@uzh.ch.
4
Department of Prosthodontics, Dental School, Ludwig-Maximilians-University Munich, Goethestrasse 70, Munich 80336, Germany. daniel.edelhoff@med.uni-muenchen.de.
5
Department of Prosthodontics, Dental School, Ludwig-Maximilians-University Munich, Goethestrasse 70, Munich 80336, Germany. marlis.eichberger@med.uni-muenchen.de.
6
Faculty of Engineering and Computer Science, Material Science and Analysis, University of Applied Sciences, Hochschule Osnabrück, Albrechtstrasse 30, Osnabrück 49076, Germany. i.m.zylla@hs-osnabrueck.de.
7
Department of Prosthodontics, Dental School, Ludwig-Maximilians-University Munich, Goethestrasse 70, Munich 80336, Germany. bogna.stawarczyk@med.uni-muenchen.de.

Abstract

The aim of this work was to evaluate the influence of specimen preparation and test method on the flexural strength results of monolithic zirconia. Different monolithic zirconia materials (Ceramill Zolid (Amann Girrbach, Koblach, Austria), Zenostar ZrTranslucent (Wieland Dental, Pforzheim, Germany), and DD Bio zx² (Dental Direkt, Spenge, Germany)) were tested with three different methods: 3-point, 4-point, and biaxial flexural strength. Additionally, different specimen preparation methods were applied: either dry polishing before sintering or wet polishing after sintering. Each subgroup included 40 specimens. The surface roughness was assessed using scanning electron microscopy (SEM) and a profilometer whereas monoclinic phase transformation was investigated with X-ray diffraction. The data were analyzed using a three-way Analysis of Variance (ANOVA) with respect to the three factors: zirconia, specimen preparation, and test method. One-way ANOVA was conducted for the test method and zirconia factors within the combination of two other factors. A 2-parameter Weibull distribution assumption was applied to analyze the reliability under different testing conditions. In general, values measured using the 4-point test method presented the lowest flexural strength values. The flexural strength findings can be grouped in the following order: 4-point < 3-point < biaxial. Specimens prepared after sintering showed significantly higher flexural strength values than prepared before sintering. The Weibull moduli ranged from 5.1 to 16.5. Specimens polished before sintering showed higher surface roughness values than specimens polished after sintering. In contrast, no strong impact of the polishing procedures on the monoclinic surface layer was observed. No impact of zirconia material on flexural strength was found. The test method and the preparation method significantly influenced the flexural strength values.

KEYWORDS:

3-point flexural strength; 4-point flexural strength; biaxial strength; flexural strength; monolithic zirconia; specimen preparation

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