Experimental Research on Grinding Surface-Quality of Dental Zirconia

The properties and cutting performance of Y2O3-stabilized tetragonal zirconia polycrystal（ Y-TZP） used widely for dental restoration have been introduced. The surface roughness of denture made by the ceramics plays an important role in product quality. In order to enhance the surface quality of denture processing,the effect of grinding parameters such as spindle speed,feed rate and the depth of cut with different levels on denture surface roughness were deeply studied to look for reasonable grinding parameters. The experiment was arranged in the orthogonal method. A new dental bur used only for dentistry was employed to carry out the experiment in a high accuracy machining center which was developed by Nanjing University of Aeronautics and Astronautics. The experimental results demonstrated that the depth of cut was the major parameter on surface roughness. With scanning electron microscope（ SEM）,it was found that the ceramics debris and its surfaces damage were mainly affected by depth of cut. The surface formation mechanism of zirconia ceramics was revealed by the morphology of machined surface. The topographies of the grinded ceramics surfaces demonstrated that zirconia ceramics was removed by its brittle fracture and plastic deformation. The plastic deformation region at grinded ceramic surface was larger with the smaller grinding depth.Finally, an example for grinding molar crown using zirconia ceramics was provided. After processing,the surface morphology of the molar crown was measured. The results showed that its quality was high and met the requirements of dental restoration. The research results of this paper provide useful and theoretical basis for denture processing.