Comparative Study On Surface Roughness Of Polishing Cercon Zirconia With Four Polishing Tools

Objective: For the patients who use cercon zirconia to repair dental defects or dentition defects or missing dentures,four different polishing sets are used to polish the surface of cercon zirconia specimens,and the surface roughness and surface morphology of the polished zirconia are compared.The polishing effect and roughness of four different polishing sets were evaluated by observing and measuring the surface roughness of zirconia by naked eye,surface profiler and scanning electron microscope.in order to reduce the bacterial adhesion on the surface of the restoration and the wear to the jaw teeth,and provide guidance and suggestions for selecting a suitable zirconia polishing suit in clinical work.Materials and methods:Cercon zirconia germ disk was cut into 13 mm × 13 mm × 6mm specimen by slow mobile phone.After sintering in the sintering furnace,the specimen size was 10 mm × 10 mm × 5mm.Use a high-speed turbine phone and a blue standard diamond needle to treat the surface of the specimen to be uniform without cracks,bumps and other defects.Fifty specimens were selected and randomly divided into five groups with 10 specimens in each group(group A,group B,group C,group D,group E).Group A was negative control group,group B was EVE group,group C was SHOFU group,group D was Toboom group and group E was NAIS group.During polishing and polishing,each vehicle is treated for 2 minutes on the surface of the specimen.After rough polishing with EVE green sand,EVE group uses pre-polishing and highlight polishing respectively to polish the surface of the specimen step by step;group B uses SHOFU vitrified diamond rough polishing,then uses white porcelain polishing wheel and rubber wheel to polish the surface step by step;group C uses Toboom green sand rough polishing and uses three-stage polishing suit to polish the specimen surface step by step.Group D was NAIS group.After rough polishing with NAIS green sand,pre-polishing and high polishing needle were used to polish step by step.All the specimens were treated once at each stage,and the surface roughness of the specimens was measured.The sampling length of the measured Ra value is 0.8mm and the evaluated length is 4mm.Three points were taken to measure the roughness on the surface of the specimen,and the average values of three points were compared.After each stage treatment,a sample was randomly selected and put into the vacuum coating instrument for surface spraying gold,and then put into the scanning electron microscope to vacuum and observe the surface morphology.The observation multiples are 300,1000 and 5000 times.The Ra value measured on the surface of the specimen was analyzed by single factor analysis of variance with SPSS 24,and the evaluation index α = 0.05 was compared by LSD-t method,and whether the roughness between the groups was statistically significant.Results:The Ra values obtained by polishing the surface of zirconia samples with different polishing sets are different,and the Ra values between different groups are statistically significant(Franch 2062.372).Final Ra value comparison: Toboom group,NAIS group < EVE group < SHOFU group < blue diamond needle group.The results of LSD-t test showed that there was no significant difference in the final Ra value between group D and group E,but there was significant difference among the other groups(P <0.05).The surface observation of the specimen was carried out by using ZYGO surface profiler.After each stage of polishing and polishing,the surface of the specimen was gradually smooth,the area of towering and pits gradually decreased,and the degree of surface smoothness was consistent with the Ra value.The surface of the zirconia polishing suit of Toboom group and NAIS group was the smoothest after polishing.Scanning electron microscope observation: the scratches left on the surface of the specimen by using the Emery needle are the deepest and longest,and the surface of the specimen can be gradually smooth by using a polishing suit,and the scratches left on the surface of the specimen will gradually become shorter and shallower.The surface of the specimen is gradually smooth and uniform.After polished by NAIS group and Toboom group,the surface of the specimen was scratched least and shallower under the mirror.Conclusion: there is a significant difference in the surface roughness of cercon zirconia polished by four different polishing suits.the polishing effect of Toboom zirconia polishing suit and NAIS zirconia polishing suit is the best,which meets the clinical requirements for roughness,and the surface of zirconia is glossy after polishing.However,because only four kinds of polishing sets are compared in this experiment,the experimental sample size is small,and further research is needed to observe other parameters such as glossiness.