Synthesis and mechanical behavior of β-tricalcium phosphate/titania composites addressed to regeneration of long bone segments

Bioactive tricalcium phosphate/titania ceramic composites were synthesized by pressure-less air sintering of mixed hydroxyapatite and titania (TiO₂) powders. The sintering process was optimized to achieve dense ceramic bodies consisting in a bioactive/bioresorbable matrix (β-tricalcium phosphate) reinforced with defined amounts of sub-micron sized titania particles. Extensive chemico-physical and mechanical characterization was carried out on the resulting composites, which displayed values of flexural strength, fracture toughness and elastic modulus in the range or above the typical ranges of values manifested by human cortical bone. It was shown that titania particles provided a toughening effect to the calcium-phosphate matrix and a reinforcement in fracture strength, in comparison with sintered hydroxyapatite bodies characterized by similar relative density. The characteristics of the resulting composites, i.e. bioactivity/bioresorb-ability and ability of manifesting biomimetic mechanical behavior, are features that can promote processes of bone regeneration in load-bearing sites. Hence, in the perspective of developing porous bone scaffolds with high bioactivity and improved biomechanical behavior, TCP/TiO₂ composites with controlled composition can be considered as very promising biomaterials for application in a field of orthopedics where no acceptable clinical solutions still exist.