Bone Tissue Response in a Metallic Bone Architecture Microstructure Tamiye Simone Goia 1, a , Kalan Bastos Violin 1,b , Carola Gomez Ágreda 1,c , José Carlos Bressiani 1,d and Ana Helena de Almeida Bressiani 1,e 1 Av. Professor Lineu Prestes, 2242, Instituto de Pesquisas Energéticas e Nucleares, São Paulo, SP, Brazil a tsgoia@ipen.br, b kbviolin@ipen.br, c cgagreda@ipen.br, d jcbressia@ipen.br, e abressia@ipen.br Keywords: Porosity, Titanium, Bone Microstructure, Natural Polymers Abstract. Porous metallic structures have been developed to mimic the natural bone architecture, having interconnected porosity, disposing enough room to cell migration, anchoring, vascularization, nourishing and proliferation of new bone tissue. Research involving porous titanium has been done with purpose to achieve desirable porosity and increasing of bone-implant bond strength interface. Samples of titanium were prepared by powder metallurgy (PM) with addition of different natural polymers (cornstarch, rice starch, potato starch and gelatin) at proportion of 16wt%. In aqueous solution the hydrogenated metallic powder (TiH 2 ) and the polymer were mixed, homogenized and frozen in molds near net shape. The water was removed in kiln and the polymer by thermal treatment in air- (350ºC/1h) before sintering in high-vacuum (1300ºC/1h). The biological evaluation was performed by in vivo test in rabbits. Histological analysis was performed by scanning electron microscopy (SEM), energy dispersive spectroscopy (SEM-EDS) and fluorescence microscopy (FM). The processing methodologies using natural low cost additives propitiate the production of porous metallic implants in a simplified manner, with different porosities, proper porosity degree (40%), distribution, and maximum pore size of 80 μm to 220 μm depending of natural polymer used. The samples added with rice starch, presented the most similar structure organization when compared to the bone tissue microstructure organization of the trabecular bone. All implants osseointegrated, the pore microarchitecture and its interconnected network allowed bone ingrowth in all pore sizes, but the continuous bone maturation occurred in pores bigger than 80 μm. Introduction Metallic biomaterials are widely used in medicine, for replacing, supporting or repairing bone tissues that were lost or suffered injuries. The main fields of application, as orthopedics and dentistry, expect from materials some desirable properties of those particular metals like mechanical strength, corrosion resistance and non-toxicity among others. The major clinical application of metallic biomaterials is as endosseous implants, for that reason, many studies research the interaction between bone and the material [1, 2, 3]. The bone tissue is the main responsible for providing stability and support to the body, being a highly specialized support tissue. The bone is a highly hierarchical nanomaterial composite, a mineralized hard tissue able to modify its own structure to meet the physical and metabolic need in response to physiological and environmental factors. The complex network of cortical and trabecular bone cannot be reproduced by alloplastic materials yet, since not only the inorganic parts are involved in that interaction, but also the organic content which have an important role on the biofunctional property of bone [4]. Architecturally and functionally, cortical bone has considerable similarity to the metallic machined implant regularly used in conventional treatment. Nevertheless the developing of a trabecular metallic structure, which mimics the architectural appearance of trabecular bone, changes the perspective of metallic biomaterials requirements to be addressed during the rehabilitation process. In the process of repair, the healing of bone-implant interface passes through the same steps as a direct bone fracture, following an orderly sequence of events. After primary stabilization and serum protein adsorption on the implant, the initial healing begins with the formation of coagulum between the bone and the implant, with subsequent clot organization allowing cells to adhere at the -RXUQDO RI %LRPLPHWLFV %LRPDWHULDOV DQG %LRPHGLFDO (QJLQHHULQJ 9RO SS 2QOLQH DYDLODEOH VLQFH -XQ DW ZZZVFLHQWLILFQHW 7UDQV 7HFK 3XEOLFDWLRQV 6ZLW]HUODQG GRLZZZVFLHQWLILFQHW-%%%( $OO ULJKWV UHVHUYHG 1R SDUW RI FRQWHQWV RI WKLV SDSHU PD\ EH UHSURGXFHG RU WUDQVPLWWHG LQ DQ\ IRUP RU E\ DQ\ PHDQV ZLWKRXW WKH ZULWWHQ SHUPLVVLRQ RI 773 ZZZWWSQHW ,' ,3(1 6mR 3DXOR %UD]LO