Methods: Four groups of 10 disc specimens (16 mm diameter x 1.2mm thickness in accordance with ISO-6872, 1995) were made from the following ceramic materials: Turkom-Cera Fused Alumina core (Turkom-Ceramic (M) Sdn. Bhd., Kuala Lumpur, Malaysia), In-Ceram core (Vita Zahnfabrik, Bad Sackingen, Germany), Vitadur-N core (Vita Zahnfabrik, Bad Sackingen, Germany) and Vitadur-Alpha veneer porcelain (Vita Zahnfabrik, Bad Sackingen, Germany), which were prepared and sintered according to manufacturer's recommendations. The specimens were subjected to biaxial flexural strength test using a universal testing machine at a cross-head speed of 0.5 mm/min. The definitive fracture load was recorded for each specimen and the biaxial flexural strength was calculated from an equation in accordance with ISO-6872.
Results: The mean biaxial flexural strength was for Turkom-Cera (506.8±87.01 MPa), In-Ceram (347.4±28.83 MPa), Vitadur-N (128.7±12.72 MPa) and Vitadur-Alpha (58.2±8.54 MPa). The results were analyzed by the Levene's test and Dunnett's T3 post-hoc test (SPSS software V11.5.0 for Windows, SPSS, Chicago, IL, USA ) at a pre-set significance level of 5 % because of unequal group variances (P<0.001). There was statistically significant difference between the core and veneer-ceramics. The biaxial flexural strength of all-ceramic core materials was significantly higher than the veneer ceramic. The mean biaxial flexural strength of Turkom-Cera was significantly higher than In-Ceram and Vitadur-N core ceramics (p<.05).
Conclusions: The results of this study are important to both dentists and technicians in order to select the most appropriate all-ceramic system. Turkom-Cera core has significantly higher flexural strength than In-Ceram and Vitadur-N core ceramics and Vitadur-Alpha veneer ceramic.
This study was supported by a grant (P0197/2006C); University of Malaya, Kuala Lumpur, Malaysia.