Property Evaluation Of Three Different Dental Co-Cr Alloy

Objective:To evaluate the physical-chemical properties,mechanical properties and metal-ceramic bonding characteristics of dental Cobalt-Chrome(Co-Cr)alloy fabricated using three different Co-Cr materials:wirobond(?)280(Bego,Germany),GIALLOY CB Blank(BK giulini,.Germany)and Remanium(?)star CL(Dentaurum,Germany).Methods:Three groups of dental Co-Cr alloy specimens were fabricated using three different dental Co-Cr materials via conventional casting,computerized numerical control milling and selective laser melting technique.Chemical composition was analysed by spectroscopy and microstructure characteristics were observed using scanning electron microscope.The density was tested using Archimedes principle and Vickers hardness was tested by hardness-testing machine.Tensile test was used to measure the tensile strength.elongation and the elastic modulus.After pro-oxidation treatment,the surface morphology of three groups was observed by SEM,and then the porcelain was fused to metal and the metal-ceramic bonding strength was assessed by three-point bending test.Fracture mode was analyzed and elemental distribution on debonding interface was assessed by SEM/EDS.The data results were statistically analyzed using one-way ANOVA(a=0.05).Results:1.Chemical composition:The chemical composition of specimens of three groups was basiclly the same before and after fabricating process,maily containing the elements of CO、Cr、W、Mo、Si etc.2.SEM:The presence of spherical pores was observed in specimens of three groups and this finding was more profound in CAST group.3.Density:The density of three groups were similar(8.46±0.18g/cm3 in CAST group,8.47 ± 0.16 g/cm3 in CNC group,8.33 ± 0.05 g/cm3 in SLM group)and no significant difference was found(P>0.05).4.Vickers hardness:The Vickers hardness of SLM group was the highest among three groups and the differences were significant(P<0.005).5.Tensile test:The tensile strength and elastic modulus of SLM group were higher than other groups,and the differences were significant(P<0.05),while the elongation of CNC group was the highest among three groups.6.Metal-ceramic interface:The metal-ceramic interface of three groups combinated closely and the elemental penetration was observed.The elements diffusion width was 12-13 μ m in CAST group,5-6 μ m in CNC group and 8-9μ m in SLM group respectively.7.Metal-ceramic bongding strength:Three point bending test results showed that metal-ceramic bonding strength of SLM group and CNC group were higher than CAST group,and the differences were significant(P<0.05).Fracture surface of all specimens exhibited a mode of cohesive failure and residual porcelain on CAST group and CNC group were much more than SLM group.Conclusion:The major chemical composition and density of three groups are the same.Mechanical properties and metal-ceramic bonding strength of dental Co-Cr alloy of SLM group are superior than the CAST and CNC group,which can be concluded that dental Co-Cr alloy fabricated using Remanium(?)star CL by selective laser melting technique shows excellent properties and worth in clinical promotion.