Fracture strength of the IPS empress crown: The effect of occlusal using depth and axial inclination on lower first molar / 대한치과보철학회지

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 lower First Molar. After 10 metal dies were made for each group, the IPS Empress ceramic crowns were fabricated and cemented with resin cement(Bistite resin cement, Tokuyama Soda Co. LTD., Japan). The cemented crowns were mounted on the testing jig with inclination of 30 degrees and the universal testing machine(Zwick Z020, Zwick, Germany)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 12degree inclination was the highest (1789 N). Crowns of 1.5 mm depth and 4degree inclination had the lowest strength (1091 N). 2. There were no significant differences in the fracture strength by axial inclination of the same occlusal depth group. 3. Most fracture lines began at the loading area and extended through proximal surface perpendicular to the margin, irrespective of occlusal depth. Size of fragment was affected by the amount of occlusal reduction.

Fracture Strength Of The Ips Empress Crown: The Effect Of Occlusal Depth And Axial Inclination On Lower Second Premolar / 대한치과보철학회지

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 degrees, 8 degrees, 12 degrees) of the lower second premolar. 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 the fracture strength. The results of this study were as follows: 1. The fracture strength of the ceramic crown with 2.5mm depth and 12 degrees inclination was the highest (1284 N).Crowns of 1.5mm depth and 8 degrees inclination had the lowest strength (951N). 2. There were no significant differences in the fracture strength by axial inclination of the same occlusal depth group. 3. Most fracture lines began at the loading area and extended through proximal surface perpendicular to the margin, irrespective of occlusal depth.

FRACTURE STRENGTH OF THE IPS EMPRESS CROWN:THE EFFECT OF OCCLUSAL DEPTH AND AXIAL INCLINATION ON UPPER FIRST PREMOLAR CROWNS / 대한치과보철학회지

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 premolar. After 10 metal dies were made for each group, the IPS Empress ceramic crowns were fabricated and each crown was cemented on each metal die 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 were : 1. The fracture strength of the ceramic crown with 2.5mm depth and 12degreeinclination was the highest (630N). Crowns of 1.5mm depth and 4degreeinclination had the lowest strength(378N). There were no significant differences of the fracture strength by axial inclination in same occlusal depth group. 2. The fracture mode of the crowns was similar. Most of fracture lines began at the loading area and extended through proximal surface perpendicular to the margin, irrespective of occlusal depth.