Assessing the cutting efficiency of different burs on zirconia substrate.

Cutting dental zirconia for endodontic access preparation is difficult. Therefore, this study aimed to determine cutting efficiency of various burs when cutting this material. An air turbine handpiece was used in a customised test rig to cut sintered zirconia specimens, using a conventional blue band diamond, two different zirconia-cutting diamond and a zirconia-cutting tungsten carbide bur. Position and speed of the bur were continuously determined using wireless data acquisition over two successive five-minute runs. Differences in cutting efficiency were statistically analysed. Burs were examined using light and scanning electron microscopy (SEM). All diamond burs cut zirconia more efficiently than the tungsten carbide bur. Overall, all burs showed decreasing cutting efficiency over time. SEM images showed discernible wear and damage to the cutting portion of each bur head. It is concluded that zirconia-cutting burs are advantageous regarding durability, and carbide burs are rather ineffective against carbide substrate.