The purpose of this study was to compare the fracture strength of the IPS Empress ceramic crown according to the occlusal depth (1.5mm, 2.0mm, 2.5mm) and axial inclination (4° , 8° , 12° ) of the lower secondpremolar.
After 10 metal dies were made for-each group, the IPS Empress ceramic crowns were fabricated and cemented with resin cement. The cemented crowns were mounted on the testing jig with inclination of 30 degrees and the universal testing machine was used to measure thefracture strength.
The results of this study were as follows
1. The fracture strength of the ceramic crown with 2.5mm depth and 12° inclination was the highest (1284 N). Crowns of 1.5mm depth and 8° inclination had the lowest strength (951 N).
2. There were no significant differences in the fracture strength by axial inclination of the same occlusal depth group, however, ther were significant differences inthe fracture strangth by occlusal depth.
3. Most fracture lines began at the loading area and extended through proximal surface perpendicular to the margin, irrespective of occlusal depth.
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