학술정보

6.1.5 Effects of surface finish and fatigue testing on the fracture strength of CAD-CAM and pressed-ceramic crowns.

6. CAD-CAM materials
6.1. CAD-CAM materials
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2019-01-01 20:04
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6.1.5

Chen HY, Hickel R, Setcos JC, Kunzelmann KH.

Effects of surface finish and fatigue testing on the fracture strength of CAD-CAM and pressed-ceramic crowns.

The Journal of prosthetic dentistry. 1999;82(4):468-75.

 

STATEMENT OF PROBLEM:

All-ceramic molar crowns can be fabricated with CAD-CAM or laboratory methods with different materials, and a polished or oven-glazed surface.

PURPOSE:

This in vitro study determined the fracture strength of various all-ceramic crowns, with and without prior cyclic loading.

MATERIAL AND METHODS:

Standardized molar crowns were fabricated with a CAD-CAM machine (Cerec 2), software with machinable ceramic materials (Vita Mark II and ProCAD), and also conventional heat-pressed IPS Empress crowns fabricated at 2 dental laboratories. Groups of 40 crowns of each material were manufactured with either a polished or an oven-glazed surface finish. Cyclic loading that simulated oral conditions were performed on half of each group. Afterward, all crowns were loaded until catastrophic failure.

RESULTS:

Fracture loads of the polished ProCAD crowns without prior cyclic loading was 2120 +/- 231 N, significantly higher than that of the polished Vita Mark II crowns (1905 +/- 235 N), but was not significantly different from the strength of 2 laboratory-fabricated Empress crowns. Oven-glazing of ProCAD crowns improved the fracture strength significantly, up to 2254 +/- 186 N. Prior cyclic loading decreased the strength of all tested crowns significantly, but the reduction was less for the Cerec crowns than the Empress crowns.

CONCLUSION:

Cerec ProCAD crowns demonstrated significantly greater strength than the Vita Mark II crowns, better resistance to cyclic loading and lower failure probability than the laboratory-fabricated IPS Empress crowns. Prior cyclic loading significantly reduced the strength of all-ceramic crowns, but had less effect on Cerec crowns than on the IPS Empress crowns. Oven-glazing of ProCAD crowns resulted in significantly higher strength and higher resistance to cyclic loading than surface polishing.

 

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