Effects of porcelain thickness on the flexural strength and crack propagation in a bilayered zirconia system
J. appl. oral sci
; 25(5): 566-574, Sept.-Oct. 2017. tab, graf
Article
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| LILACS, BBO
| ID: biblio-893657
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ABSTRACT
Abstract Objective:
This study evaluated the influence of porcelain (VM9, VITA Zahnfabrik, Germany) thickness on the flexural strength and crack propagation in bilayered zirconia systems (YZ, VITA Zahnfabrik, Germany). Material andMethods:
Thirty zirconia bars (20.0x4.0x1.0 mm) and six zirconia blocks (12.0x7.5x1.2 mm) were prepared and veneered with porcelain with different thickness 1 mm, 2 mm, or 3 mm. The bars of each experimental group (n=10) were subjected to four-point flexural strength testing. In each ceramic block, a Vickers indentation was created under a load of 10 kgf for 10 seconds, for the propagation of cracks.Results:
The results of flexural strength were evaluated by One-way ANOVA and Tukey's test, with a significance level of 5%. The factor "thickness of the porcelain" was statistically significant (p=0.001) and the l-mm group presented the highest values of flexural strength. The cracks were predominant among the bending specimens with 1 and 2 mm of porcelain, and catastrophic failures were found in 50% of 3-mm-thick porcelain. After the indentation of blocks, the most severe defects were observed in blocks with 3-mm-thick porcelain.Conclusion:
The smallest (1 mm) thickness of porcelain on the zirconia infrastructure presented higher values of flexural strength. Better resistance to defect propagation was observed near the porcelain/ zirconia interface for all groups. Higher flexural strength was found for a thinner porcelain layer in a bilayered zirconia system. The damage caused by a Vickers indentation near and far the interface with the zirconia shows that the stress profiles are different.Palabras clave
Texto completo:
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Índice:
LILACS
Asunto principal:
Circonio
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Cerámica
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Porcelana Dental
Tipo de estudio:
Evaluation_studies
Idioma:
En
Revista:
J. appl. oral sci
Asunto de la revista:
ODONTOLOGIA
Año:
2017
Tipo del documento:
Article