| Dental Zirconia ceramic material has been widely applied in prosthetic field inrecent years,since it has prominent machnical properties.However,the bond strengthbetween Y-TZP and resin cement is not so stable when applied,more effectivemethods are required to be researched to enhance the strength.Objectives: the objectives of the present study were:①to evaluate the surfacemorphology,roughness and crystal form of zirconia applied the SiO2-ZrO2coatingtreatment.②to evaluate the resin bond strength and durability of bonding betweenzirconia and resin cement with SiO2-ZrO2coating treatment.Materials and Methods: two hundred and ten discs(15mm*15mm*2mm) ofpresintered zirconium-oxide were equally divided into7groups(n=30) and thesurfaces were treated separately by the following methods:①AS:one side of thesurfaces milled with800mesh sandpaper then fully sintered;②SB:fully sintered thensandblasted by110μm Al2O3particles for10s;③2SiO2-1ZrO2:coated with slurrycontaining sillicon dioxide and zirconia powder prepared with2:1molar ratio thensintered according to the above method.④1SiO2-1ZrO2:coated with slurry containingsillicon dioxide and zirconia powder prepared with1:1molar ratio then sinteredaccording to the above method.⑤1SiO2-2ZrO2:coated with slurry containing sillicondioxide and zirconia powder prepared with1:2molar ratio then sintered according tothe above method.⑥1SiO2-3ZrO2:coated with slurry containing sillicon dioxide andzirconia powder prepared with1:3molar ratio then sintered according to the abovemethod.⑦1SiO2-4ZrO2:coated with slurry containing sillicon dioxide and zirconiapowder prepared with1:4molar ratio then sintered according to the above method.Ten of Each group were chosen to be examined the surface morphology usingscanning electron microscopy, determined the mean surface roughness(Ra) using aprofilometer,analysed the surface crystallographic phase using X-ray diffractionanalysis.The rest twenty discs of each group were etched by9.5%hydrofluoricacid,then bonded to composite resin cylinders with resin cement.Shear bond strengthwas tested in a universal testing machine after24h of37℃water storage and5,000thermal cycles.Examine the failure mode.Statistical analysis was performed using aone-way analysis of variance(AN0VA) model with α=0.05.Results:①grains were compact in group AS.surface was covered withinnumerable irregular grooves and cracks were found in some local places in groupSB.the surfaces of coating groups were covered with unformed SiO2before etched by HF.After etched by the HF,the grains were exposed,according to the change of SiO2content in coating slurry,the gaps between zirconia grains become more and morelarger.②Only Zr and O were detected on the surface of group AS.Al,Zr and Si wasdetected on the surface of group SB.Different Si content was detected on the surfaceof coating groups from0.65%to15.07%.③The surfaces of group AS and all coatinggroups were consisted of100%tetragonal zirconia.Monoclinic phase was observed onthe surface of group SB.④The lowest roughness(0.334μm) was found on the surfaceof group AS.Group1SiO2-2ZrO2had a highest roughness(4.064μm).There were nostatistically significant differences among2SiO2-1ZrO2,1SiO2-1ZrO2and1SiO2-2ZrO2.⑤Before the thermal cycle,group1SiO2-4ZrO2had the lowest shearbond strength(7.37Mpa).Group1SiO2-1ZrO2achieved the highest bondstrength(41.69Mpa).The shear bond strength transformed from increasing todecreasing according to the decreasing of the SiO2content of coating slurry. After thethermal cycle, Group2SiO2-1ZrO2had the highest bond strength,but had nosignificant differences with group1SiO2-1ZrO2and group1SiO2-2ZrO2(P>0.05).Conclusion:①SiO2-ZrO2coating can significantly increase the surfaceroughness and produce a porous surface in a nondestructive approach.②theSiO2-ZrO2coating technique is a effect approach to improve the shear bond strengh tozirconia surface. |
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