J Korean Acad Prosthodont.
2001 Apr;39(2):171-183.
Fractures Strength Of The Ips Empress Crown : The Effect Of Occlusal Depth And Axial Inclination On Upper First Molar
Abstract
- 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 (4degree , 8degree, 12degree)of the upper first molar. After 10 metal dies were made for each group, the IPS Empress ceramic crowns were fabricated and were cemented with resin cement. The cemented crowns mounted on the testing jig were inclined 30 degrees and a universal testing machine was used to measure the fracture strength.
The results of this study were as follows :
1. The fracture strength of the ceramic crown with 2.5mm depth and 8degree inclination was the highest (1393N). Crowns of 1.5mm depth and 4degree inclination had the lowest strength (1015N).
2. There were no significant differences of the fracture strength according to occlusal depth and axial inclination.
3. Most fracture lines began at the loading area and extended through proximal surface perpendicular to the margin, irrespective of occlusal depth.
4. There was positive correlation between the fracture strength and the fracture surface area of crowns.