Effect of medical polymer filling on tensile properties of biomedical porous pure titanium

High Young's modulus of metallic biomaterials in comparison with that of bone affects harmfully on bone healing and remodeling. Therefore, it is important to decrease Young's modulus of the metallic biomaterials. In that case, porous materials are advantageous from the viewpoint of obtaining a lower Young's modulus, because Young's modulus decreases with increasing porosity of the porous materials. However, with an increase in porosity, the other mechanical properties start deteriorating simultaneously. This deterioration of the mechanical properties is probably derived from the stress concentration at the pores of the porous materials. In comparison with metallic biomaterials, polymers exhibit lower Young's moduli; thus a polymer filling is a likely option to improve the mechanical properties of porous materials by preventing the stress concentration at the pores without increasing the Young's modulus. Furthermore, certain polymers exhibit intrinsic biofunctionalities, Thus, polymer filling is expected to improve the mechanical properties and impart biofunctionalities to porous materials without an increase in its Young's modulus. In this study, the pores of porous pure titanium (pTi) with the porosity of 22-50% were filled with a medical polymer (polymethylmethacrylate: PMMA). The effects of PMMA filling on the tensile strength and Young's modulus of pTi were then investigated. As a result, it is found that the PMMA filling improves the tensile strength of pTi with the porosity over 40%, although not significantly affecting the Young's modulus of pTi.