The Effects Of Different Surface Processing On Bond Strength Between Zirconia Framework And Veneering Ceramic

Objective:To compare the effects of different surface treatments on bond strength and the microscopic structure with a scanning electron microscope(SEM) and an energy distribution spectrum(EDS) at the bonding interface between zirconia framework and veneering ceramic.Methods:The WIELAND zirconia core material was cutted into thirty rectangular specimens(12mm×6.25mmx6.25mm)and fired on into rectangular specimens (10mmx5mmx5mm). The specimens were divided into three groups randomly(n=10 per group). The sandblasting group was sandblasted before firing.The sandblasting and liner coverage group was sandblasted before firing and then sintered liner coversge after firing. The control group was no treatment.All the veneering ceramics were fired on the zirconia substructure by slip -casting technique.One bilayered specimen in every group was prepared for scanning electron microscope (SEM)and energy distribution speetrum(EDS)to investigate the bonding conditions. All of the specimens were measured to shear force in an electronic universal dynamometer.The obtained data was analyzed by using the statistical softure SPSS17.0.Results:1. The result of the shear bond strength testThe values of shear bond strength test were (18.06±0.59) Mpa for the sandblasting group, (21.04±1.23) Mpa for the sandblasting and liner coverage group, (13.80±1.54)Mpa for the control group,significant difference existed between each group (P<0.05).2. The result of scanning electron microscopeThe surface of zirconiaThe sandblasting and liner coverage group:The surface of zirconia formed the irregular concave and convex.The control group:The surface of zirconia can see clearly visible groove and ridge but the depth is not obvious.The bonding interfaceThe sandblasting and liner coverage group:The combination interface is closely without clearance and obvious mosaic fusion.The control group:The combination interface is relatively flat and more closely and no obvious mutual penetration chimeric.3. Ther result of energy distribution spectrum.The sandblasting group:The result of EDS showed the conent of zirconium descended sharply at the interface,a microscale of zirconium was detected in the veneering layer;the content of silicon decreased rapidly at the combination interface,and a small quantity of silicon can be detected in the zirconia framework; the content of aluminum descended slowly at the interface.The sandblasting and liner coverage group:The result of EDS showed the content of zirconium increased in the veneering layer and descended sharply at the interface; the content of silicon decreased rapidly at the combination interface,and a small quantity of silicon can be detected in the zirconia framework; the content of aluminum descended slowly at the interface.The control group:The result of EDS showed that the conent of zirconium descended sharply at the combination interface,and the zirconium was not detected in the veneering layer; the conent of silicon descended rapidly at the combination interface,and the silicon can be detected in the zirconia framework; The content of aluminum descended slowly at the interface.Conclusions:1. Abrasion before firing can significantly increase the shear bond strength of zirconia to veneering porcelain.2. The use of porcelain combined with liner can increase the shear bond strength.