Influence of different thickness on the flexural strength of zirconia ceramics

The aim of this project was to evaluate and compare the different thickness of zirkonzahn ceramics and its mechanical properties of ceramics, which have generated interest in restorative dentistry because of their high strength and high resistance to fracture.Three different thickness and 10 samples of zirkonzahn ceramic were selected for this study (15x0.3mm), (15x0.5mm), (15 x0.7mm) Three control discs of the green stage Zirconia block were cut with saw (leitz 1600) and sintered in zirkonzahn sintering oven start at 20- 1500 ?C. All discs were polished with diamond paste. The cycle of all processes take 8 hrs and this procedure were provided by (zirkonzahn Furnace). The surface of the Zirconia specimens were ground with 600, 800, 1200 (Silver carbide abrasives) under water cooling and then with 120 ?m Al2O3 particles are blasted to 0.5 MPa pressure from a distance of 10 mm, 15 seconds.The evaluation data were performed by NCSS (Number Crunchers statistical system) 2007&PASS 2008 Statistical Software (Utah, USA) program. The evaluation of operating data, comparisons between groups one-way analysis of variance (one way ANOVA) test and Tukey HDS test was used for the determination of the group that lead to differences. Pearson correlation analysis was used for assessing the relationships between parameters p <0.05 level were evaluated.The mean biaxial flexural strengths of ten discs are presented in all groups. The highest mean biaxial flexural strength found at 0.7mm than at 0.5 mm and lowest value was found at 0.3mm. A cording to our results; increasing the core thickness of Zirconia from 0.3 to 0.5mm flexural strength was increased 7%. But core thickness did not differ between 0.5mm and 0.7mm, Which revealed no significant difference between the fracture strength values of the test groups (P>.05).In this study the Increasing the core thickness from 0.3 to 0.5 has shown 7% increase at the flexural strength and the Increasing the core thickness from 0.5 to 0.7 mm has shown no differences at the flexural strength. Result of this in-vitro study shows that increasing the thickness of zirconia from 0.3 mm to 0.5 or 0.7 mm it does not appear to be significant effect on flexural strength.