IPS e.max Press showed better wear resistance than Procera AllCeram in a clinical trial published in Journal of Prosthetic Dentistry (February 2010, Vol. 103:2, pp. 80-90).
Researchers from the University of Saskatchewan and King's College London Dental Institute randomly divided 90 posterior teeth requiring crowns in 48 patients into 3 equal groups.
The first group received IPS e.max Press (Ivoclar Vivadent), a pressed glass ceramic based on a modified lithium disilicate ceramic. The second group got Procera AllCeram (Nobel Biocare), an alumina-coping-based ceramic. The third got Simidur S 2 (Wieland Dental) veneered with IPS Classic Porcelain (Ivoclar Vivadent), a metal ceramic.
The researchers used modified U.S. Public Health Service (USPHS) criteria to assess the crowns over the course of three years. They sectioned and removed crowns that showed cracks, and analyzed the surfaces with a scanning electron microscope (SEM).
They found that the clinical behavior of the IPS e.max Press crowns was comparable to Procera AllCeram and metal ceramic crowns, but the wear resistance of this crown type was superior to the Procera AllCeram crowns.
Clear wear facets showed up in the SEM images for both types of ceramic crown, but the IPS e.max Press and metal ceramic crowns had fewer clinical changes than AllCeram crowns, the researchers wrote. They noted visible roughness, wear, and deformity in occlusal contact areas of the Procera AllCeram crowns.
"IPS e.max Press crowns demonstrated clinical behavior comparable to Procera AllCeram and metal ceramic crowns," they concluded. "But the wear resistance of this crown type was superior to the Procera AllCeram crowns, according to modified USPHS criteria."
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