| BackgroundWith the continuous updating of oral prosthetic technology and the development of oral materials science,all-ceramic restoration technology has gradually become an ideal repair method in oral prosthetic treatment.Among many ceramic restoration materials,zirconia materials stand out from many ceramic materials because of their high strength,good toughness and good biocompatibility,making them widely used in stomatology and oral biomedical fields.For example,it is clinically applied to crown and bridge repair of dental and dentition defects and as an implant to repair maxillofacial tissue defects.In recent years,as people’s requirements for aesthetics are getting higher and higher,the aesthetics of oral prosthetic treatment has become a key criterion for evaluating the success of repair treatment.Thus,the ST zirconia ceramic material gradually goes into the field of entrance cavity repair.Studies have shown that the mechanical strength of the ST zirconia will be changed while grinding by diamond burs and glazing on the surface of the material,but the specific reasons have not been clearly determined.In this study,ST zirconia were grinding in small grit and glazing,and how these treatments influent their mechanical properties.ObjectiveThis experiment intends to observe the surface morphology,surface roughness,nano-hardness,nano-modulus,phase variables,bending strength of ST zirconia ceramic materials after small-grit grinding and glazing of ST zirconia.The effects of small-grit grinding and glazing on the mechanical properties of ST zirconia were investigated by the changes in the materials and the low-temperature degradation properties of the materials.MethodsFirst,the ST zirconia of the experimental group was polished with a particle size of 320#and 2000#silicon carbide waterproof sandpaper,and the control group was not grinded with small grit.The experimental and control samples were glazed by the same dental technician.Finally,the experimental and control materials were hydrothermally treated at 134℃ and 0.2 MPa for 5 h.After the above treatment,the surface morphology and microstructure were observed,and the phase variables,nanohardness,nanomodulus and bending strength were observed.ResultsThe small grit grinding of the ST zirconia did not cause a significant phase change of the samples,but the surface topography of the material became flat,and the flexural strength,low-temperature degradation resistance,nano-hardness and nano-modulus of the material were significantly improved.Although glazing can improve the low-temperature degradation resistance of the material to a certain extent,the mechanical properties of the material such as flexural strength are significantly reduced after the glazing of the ST zirconia.Conclusion1.After the ST zirconia is grinded by small grit,the mechanical properties of the material are improved.2.The ST zirconia is glazed after being grinded by a small grit,and the mechanical properties of the material are degraded.3.After the ST zirconia is grinded by small grit,the material’s resistance of low temperature degradation and mechanical strength has been improved;ST zirconia ceramic material after small-grit grinding and glazing,the material’s resistance of low temperature degradation has been improved,but the overall mechanical strength of the materials are reduced.Clinical significance1.This study explores the effect of small particle size/ultra-small particle size grinding on the mechanical properties of ST zirconia ceramic materials.It is found that small particle size/ultra-small particle size grinding is beneficial to improve the mechanical properties of materials and guide clinicians to choose reasonable ST zirconia grinding tool.2.This study explores the effect of glazing on the mechanical properties of ST zirconia after grinding with small-grit grinding/super-small-grit grinding.It is found that glazing after grinding is not conducive to improving the mechanical properties of the material,and help the clinician decides weather glazing of the restoration.3.This study provides a reference for the selection of suitable surface treatment methods for ST zirconia in clinical work,which is beneficial to improve the service life of clinical restorations. |
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