| Objective: In this study,we investigated the effects of grinding polishing and aging on the physical properties,including the surface morphology,surface roughness,crystal phase composition,nano hardness,nano modulus,and flexural strength of two clinically commonly used types of self-made high translucent aesthetic zirconia materials and glass ceramics,and evaluated the excellent properties of the self-made materials by determining the effects of grinding polishing and aging on the physical properties of the four materials,to provide theoretical support for the choice of all ceramic materials by clinical practitioners and the variation of all ceramic materials during use after grinding polishing.Methods: Samples were prepared using 3% yttrium oxide stabilized zirconia(3Y-TZP)ceramic powder with 0.25 wt% alumina content completed by ball milling pelletization.Each weighed 2 g and was pressed into round pieces of 2 mm height by a fully automated powder press.PARAFICM membrane wrapped samples were put into an electrically cold isostatic press for 1 min under cold isostatic pressure at20 MPa,and required to step to 20 MPa in 10 min.Dry at room temperature after absolute ethanol spray cleaning for further use.The UPCERA and WIELAND zirconia materials were cut by CAD / CAM into pieces 20 mm in diameter and 2 mm in height.The above three materials were polished with 320 mesh silicon carbide sandpaper to eliminate any initial errors.Sample specifications were checked using vernier calipers,and samples that met the criteria were enrolled in this trial.The three kinds of samples were sintered in a high temperature box resistance furnace with a heating rate of 3 ° C / min,holding at 600 ° C for 1 h,continuing to heat up to 1450 ° C for 2 h,and finally cooling down with the furnace.According to ISO 6872-2015 standard,the specimens with diameter of 12 mm(± 0.2 mm)and height of 1 mm(± 0.2 mm)after sintering were selected in this experiment.Glass ceramic materials twenty specimens with 12 mm diameter(± 0.2 mm)and 1 mm height(± 0.2 mm)that had been die cast according to the specification requirements were purchased directly.The specimens were randomly divided into groups a,B,and C.Group A was the blank control group without any treatment(10 pieces of self-made sample in group A1,10 pieces of UPCERA zirconia material in group A2,10 pieces of WIELAND zirconia material in group A3,and 10 pieces of glass-ceramic in group A4).Group B was the clinical negative control group,which simulated clinical grinding and polishing and was briefly grinding polished(10 pieces of UPCERA zirconia material in group B1,10 pieces of WIELAND zirconia material in group B2,and 10 pieces of glass-ceramic in group B3).Group C was the experimental grinding polishing group with 10 pieces of self-made samples.The surface treatment way was blank control group group A without grinding.The clinical negative control group B and the experimental grinding polishing group C were ground using a semiautomatic grinding machine.The top and bottom surfaces were ground at 600 r / min for 1 min.Grinding was followed by polishing using an automatic metallographic specimen mill.The top and bottom surfaces were polished at a speed of 1000 r / min for 2 min.Finally,all materials were hydrothermally aged in water at 134 ° C for 5 h to observe the surface morphology,surface roughness,crystal phase composition,nano hardness,nano modulus and flexural strength.Results: 1.Polishing after grinding improves the surface morphology and roughness of the four transparent all ceramic materials,eliminates the initial scratches caused before sintering and flattens the surface,but produces new regular scratches(P<0.05);After grinding and polishing,the surface will become smoother after aging(P<0.05).2.After polishing,the phase transformation of zirconia and glass-ceramic will not be induced,but the aging resistance of zirconia can be improved.3.The permeability of self-made high translucent aesthetic zirconia is better than that of clinically used high translucent aesthetic zirconia and glass ceramics.4.Grinding,polishing and aging had no effect on the nano hardness and nano modulus of zirconia and glass-ceramic materials(P>0.05).The nano hardness and nano modulus of self-made zirconia materials were not different from those of high translucent aesthetic zirconia commonly used in clinic(P>0.05),but better than glass-ceramic(P<0.05).5.The flexural strength of the self-made samples was less than that of the two common clinical all ceramics,but greater than that of glass ceramics(P<0.05);Only the self-made high translucent aesthetic zirconia was polished after grinding to increase the bending strength(P<0.05),and the other three materials had no significant change(P>0.05).6.Polishing after grinding will affect the cracks near or far from the fracture.The cracks are regular and the direction is more consistent;Aging has greatly changed the fracture morphology of the sample,the surface is uneven,and even small hills and fractures appear.Conclusions: 1.The permeability of self-made high translucent aesthetic zirconia is better than that of high translucent aesthetic zirconia materials and glass ceramics in the clinical control group.The bending strength of the self-made sample is worse than that of the super transparent zirconia in the clinical control group and better than that of glass ceramics.2.The nano hardness and nano modulus of self-made zirconia materials are no different from those of high translucent aesthetic zirconia commonly used in clinic,but better than glass ceramics.3.Grinding and polishing are beneficial to improve the strength of self-made super transparent zirconia and the anti-aging properties of three zirconia materials.In conclusion,the self-made samples show excellent permeability and nano hardness and nano modulus,and also have anti-aging properties.4.Polishing after grinding improves the surface morphology and roughness of four transparent all ceramic materials.The study of lapping and polishing also provides theoretical support for the selection of all ceramic materials and the changes in the use of all ceramic materials after grinding and polishing. |
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