الفهرس 
Fracture Resistance of Pressed Zirconia Reinforced Lithium Silicate Crowns Versus Pressed Lithium Disilicate Crowns Under Thermo- Mechanical Cycling: An in vitro study
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Abstract
Aim: The present study was conducted to assess the fracture resistance of zirconia reinforced lithium silicate all ceramic material 2Celtra Press3 compared to lithium disilicate one 2IPS e-max Press3 under simulated oral conditions (thermal cycling and cyclic loading). Methodology : Fourteen ceramic crowns were fabricated on epoxy dies which were duplicated from stainless steel master die and divided into two equal groups (n=7) according to the material of construction; group A: Crowns fabricated with IPS e-max Press material and group B: Crowns fabricated with Celtra Press material.The crowns were then cemented onto their corresponding dies using with a self-adhesive resin cement (Calibra Universal) and subjected to thermocycling and cyclic loading to simulate the clinical conditions.Then they were loaded to fractur in a universal testing machine.The results were tabulated and statistically analyzed using Kolmogorov-Smirnov and Shapiro-Wilk tests. Student t-test used to compare mean values.The significance level was set at P{u2264} 0.05 and 95% Confidence interval. Statistical analysis was performed using Graph Pad Instat (Graph Pad, Inc.) software for windows Results: The mean ± SD values of fracture resistance were recorded for lithium Disilicate group (1706.01 ±154.32 N) meanwhile the mean ± SD value recorded with celtra group were (1550.67±196.71 N). It was found that e.max group recorded statistically non-significant higher fracture resistance mean value than celtra group as indicated by t-test (t=1.5, P=0.1590 > 0.05)