Comparison Of Surface Roughness And Morphology Of UPCERA Zirconia Polished By Different Polishing Grinding Heads

Objective: In this experiment,the effects of different polishing tools on the surface morphology of zirconia after polishing were studied from the two aspects of surface roughness and surface morphology by simulating the clinical adjustment and polishing operation process,thus providing guiding suggestions for the polishing of clinical zirconia restorations.Methods:1.Prepare 30 UPCERA zirconia standard specimens with a volume of 10mm×10mm×5mm,and select a 10mm×10mm surface as the experimental surface.According to the final operation before leaving the factory when the zirconia full crown is manufactured in the technical room,all test blocks are polished,sintered and glazed.After glazing,5 pieces of test pieces were randomly selected and designated as group a,group a was the blank control group,i.e.no treatment was done after glazing.2.The remaining 25 test pieces were all polished with Tob green sand and gravel to simulate the grinding operation during clinical crown wearing.After polishing,they were randomly divided into 5 groups(group B,group C,group D,group E and group F),with 5 test pieces in each group.Group B is a negative control group,i.e.no other treatment after polishing;Group C is Tob rough polishing group,Group D is Tob rough polishing+fine polishing group,Group E is SHOFU rough polishing group,and Group F is SHOFU rough polishing+fine polishing group.3.Test the surface roughness Ra value of each group of test pieces after polishing treatment and carry out one-way variance analysis.LSD-t test is used for comparison between the two groups.4.The roughness values of all groups were compared with those of existing natural teeth in the literature.5.Scanning electron microscope was used to observe the surface morphology of each group of specimens after treatment,and comparison was made.Results:1.The Ra values of surface roughness in groups A,B,C,D,E and F were(0.18±0.04),(1.17±0.08),(0.52±0.06),(0.45±0.08),(0.22±0.04)and(0.20±0.03)μm.The Ra value of group A was the lowest,and the difference was statistically significant compared with the other five groups(P<0.05).The Ra value of group B was the largest,while the Ra value of group C,D,E and F decreased successively.The difference between group B and group C,D,E and F was statistically significant(P<0.05).The difference between group C,group E and group F was statistically significant(P<0.05).The difference between group D and group E and F was statistically significant(P<0.05).There was no significant difference in Ra between group A and group E,group A and group F(P>0.05),group C and group D,and group E(P>0.05).2.According to the existing liteture,the reference value of Ra of axial enamel is 0.36±0.043μm;The Ra value of enamel in occlusal contact area was 0.64±0.25μm.Ra value of group A,E and F is less than that of axial enamel.Ra values of group A,C,D,E and F are smaller than enamel Ra values in occlusal contact area.The Ra value of group B was significantly higher than that of enamel.3.SEM observation results: the surface of group A was smooth and smooth without scratches.Group B has deep and large scratches and pits on the surface;The number of scratches in group C and group D became smaller.The scratches in group E were uniform,and the pits were reduced.Group F had the fewest scratches,which became shorter and smooth.SEM results are in good agreement with surface roughness test results.Conclusion:1.Different systems of UPCERA zirconia polishing grinding heads have different polishing effects on zirconia after grinding.Polishing effect order: SHOFU rough polishing+fine polishing group >SHOFU rough polishing group>Tob rough polishing+fine polishing group>Tob rough polishing group.2.The effect of the four polishing groups is better than the roughness of the occlusal surface of the natural teeth,which will not cause excessive abrasion to the jaw teeth.3.Glaze and pine wind groups are lower than the roughness of natural tooth axial surface,which can be inferred not to be higher than the bacterial adhesion of natural teeth.4.The Ra value of the grinding-only and non-polishing group is significantly higher than that of the enamel occlusal surface and axial surface,so grinding-only and non-polishing will not only aggravate the abrasion of natural teeth but also increase bacterial adhesion.