Study of Biocompatibility of Titanium Alloys for Biomedical Application

Method: Five groups of porous samples were manufactured by powder metallurgy: 1) control - commercially pure titanium (TiCP); 2) Ti-6Al-4V alloy (titanium-aluminium-vanadium); 3) Ti-13Nb-13Zr alloy (titanium-niobium-zirconium); 4) Ti-35Nb alloy (niobium); 5) Ti-35Nb-7Zr-5Ta alloy titanium-niobium-zirconium-tantalum). Samples were characterized by scanning electron microscopy (SEM) and energy dispersion spectrophotometry (EDS). They were evaluated for cytotoxicity on rat calvaria osteogenic cells after 3 and 10 days, and nodules formation and quantification of mineralization after 14 days.  Cells were cultivated on 18 samples of each group.  Data were analyzed by  ANOVA one way, ANOVA two ways and Tukey tests (p<0.05). 

Result: EDS detected presence of specific ions for each alloy and MEV showed an interconnected porous structure, demonstrating the effectiveness of the powder metallurgy technique. In vitro tests revealed similar biocompatibility among different alloys. Alizarin red analysis showed mineralized matrix formation  similar in TiCP, Ti-35Nb-7Zr-5Ta, Ti-35Nb, and Ti-13Nb-13Zr. Ti-6Al-4V showed the significant highest value in this analysis. MTT assay demonstrated significant interaction between time and alloy by ANOVA two ways. Tukey test revealed that Ti-6Al-4V, at 10 days, showed lower cell viability when compared to the other groups at 3 days and similar viability when compared to other groups at 10 days. The results indicate that the alloys did not show cytotoxicity under static culture conditions, comparing to the standard alloy Ti-6Al-4V. This cytocompatibility was correlated with nodules of mineralization in all groups. 

Conclusion: porous TiCP, Ti-35Nb-7Zr-5Ta, Ti-35Nb, Ti-13Nb-13 Zr and Ti-6Al-4V alloys specimens induce favorable cellular response with mineralized matrix formation. These alloys are biocompatible and have great potential for employment in biomedical implants.