Biaxial flexural strength of zirconia
ceramic with differences in core : veneer
ratio
Authors :
- Prarom Salimee D.D.S., Ph.D.
- Teera Thammawasi D.D.S.
Abstract :
Objective To investigate the biaxial flexural strength (BFS) and mode of fracture of zirconia ceramic with different thickness of core: veneer ratio.
Materials and methods Fifty disc specimens (15 mm. in diameter and 1.2 mm. in thickness) of zirconia ceramic were fabricated for 5 groups (n=10) according to core:veneer ratio; group 1 = 1:0 (core alone), group 2 = 2:1 (core 0.8 mm) group 3 = 1:1 (core 0.6 mm.), group 4 = 1:2 (core 0.4 mm.) and group 5 = 0:1 (veneer porcelain alone). All specimens were subjected to biaxial flexural test following ISO 6872: 1995 until failure occurred and calculated the BFS. All tests were carried out on the Instron 5566 with crosshead speed of 1.0 mm/min.
Results The means BFS ± SD of group 1-5 were 921.48 ± 106.86 MPa, 1009.49 ± 98.72 MPa, 895.68 ± 92.96 MPa, 768.08 ± 73.17 MPa and 70.49 ± 8.54 MPa, respectively. ANOVA and Tamhane test revealed that there was no significant difference among the BFS of group 1, group 2 and group 3 (p > 0.05) but the BFS of these groups were significantly higher than the BFS of group 4 and group 5 (p < 0.05).
Conclusion In case of specimen with 1.2 mm. in thickness, the difference of core and veneer ratio 1:0, 2:1 and 1:1 did not affect the BFS, but decreasing in thickness of core and veneer ratio to 1:2, the BFS of zirconia ceramic was significantly decreased. Delamination of core-veneer interface can be observed in all core-veneer specimens.
(CU Dent J. 2011;34:75-86)
Keywords :
Biaxial flexural strength; Core:veneer ratio; Zirconia ceramic
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