Effect Of Different Polishing Tools On The Surface Properties Of Wieland Zirconia After Polishing

ObjectiveThe purpose of this experiment was to determine the influence of the surface morphology and mechanical properties by simulating clinical blending and polishing process on the four aspects:surface roughness,scanning electron microscope(SEM),phase transformation analysised by X-ray diffraction(XRD)and vickers hardness.MethodsPreparing zirconia of wieland blocks which size was 13mm×10mm*3mm by slow grinding machine,then the operation surface of the blocks was polished by 150~#,400~#,600~#,800~#,and 1200~#sandpaper one after another.Selecting 32 specimens were randomly divided into 4 groups(A,B,C,D),8 specimens per group after the blocks sintering.Group A was blank control group without any treatment;and group B being the negative control group with the green sand and white sand polishing in turn.On the basis of group B,C,D groups were polished with the KOMET,EVE zirconia polishing suit respectively.Then the effect of polishing was measured with the surface roughness of Ra value,with the vickers hardness measuring for statistical analysis and surface morphology in each group was observated by the SEM,with XRD analysing the phase transformation.ResultsAfter surface treatment,the surface roughness of Ra values of zirconia specimens were not exactly the same,and the differences were statistically significant(F=273.2,P=0.000).For surface roughness the mean Ra values of each group with LSD-T test were as follows:D<A,B,C,and the differences were statistically significant.And the Ra values of each group for before and after polishing with two independent samples of paired t test showed that B,C,D,there groups the Ra values statistical differences.The results of SEM were consistent with the surface roughness.There was m-t phase transformation seen after the blending and polishing procedure.The hardness values of zirconia specimens were the same after surface treatment,and the difference was not statistically significant(F=2.603,P=0.053>0.05),which meant the vickers hardness value having not changed after different surface treatment.ConclusionsThe effects of different polishing tools on the zirconia of wiland were significant.EVE zirconia polishing tool achieved the best performance,which was comparable to the surface properties of zirconia after sintering.There was a transformation of m-t,and there was no m phase after polishing with detecting by XRD.The surface vickers hardness of zirconia did not change after polishing.