Abstract
The diamond burs of two dental CAD/CAM systems (GN and CD) were examined if they could be used to fabricate up to 21 ceramic full crowns without fracture. After one, 11, and 21 machining times, the surfaces of the diamond burs were observed and the number of particles captured on SEM pictures was counted. The average surface roughness of the crowns was also measured. All diamond burs could be used to fabricate 21 ceramic crowns without fracture. A significant decrease in the number of diamond particles was found on the surfaces of GN burs after 11 and 21 machining times, but not on those of CD burs. The average surface roughness of GN crowns significantly increased with increase in the number of machining times. A significant positive correlation was found between the average surface roughness and the number of diamond particles.
