Abstract
Titanium (Ti) and Ti-6 Aluminium-4 Vanadium alloys are the most common materials in implants composition but β type alloys are promising biomaterials because they present better mechanical properties. Besides the composition of biomaterial, many factors influence the performance of the biomaterial. For example, porous surface may modify the functional cellular response and accelerate osseointegration. This paper presents in vitro and in vivo evaluations of powder metallurgy-processed porous samples composed by different titanium alloys and pure Ti, aiming to show their potential for biomedical applications. The porous surfaces samples were produced with different designs to in vitro and in vivo tests. Samples were characterized with scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and elastic modulus analyses. Osteogenic cells from newborn rat calvaria were plated on discs of different materials: G1—commercially pure Ti group (CpTi); G2—Ti-6Al-4V alloy; G3—Ti-13 Niobium-13 Zirconium alloy; G4—Ti-35 Niobium alloy; G5—Ti-35 Niobium-7 Zirconium-5 Tantalum alloy. Cell adhesion and viability, total protein content, alkaline phosphatase activity, mineralization nodules and gene expression (alkaline phosphatase, Runx-2, osteocalcin and osteopontin) were assessed. After 2 and 4 weeks of implantation in rabbit tibia, bone ingrowth was analyzed using micro-computed tomography (μCT). EDS analysis confirmed the material production of each group. Metallographic and SEM analysis revealed interconnected pores, with mean pore size of 99,5μm and mean porosity of 42%, without significant difference among the groups (p>0.05). The elastic modulus values did not exhibit difference among the groups (p>0.05). Experimental alloys demonstrated better results than CpTi and Ti-6Al-4V, in gene expression and cytokines analysis, especially in early experimental periods. In conclusion, our data suggests that the experimental alloys can be used for biomedical application since they contributed to excellent cellular behavior and osseointegration besides presenting lower elastic modulus.
Highlights
The use of implants for rehabilitation of lost body structures has shown remarkable advances, providing better quality of life for patients and longevity to implants [1,2,3,4,5,6]
We reported the development of a new design for Ti implants with porous surface integrated to dense core, in order minimize the difference of elastic modulus between metallic alloy and bone [20]
As previously demonstrated by our research group[20], the implants with porous surface integrated with a dense core do not exhibit fracture line between the surface and core (Fig 4)
Summary
The use of implants for rehabilitation of lost body structures has shown remarkable advances, providing better quality of life for patients and longevity to implants [1,2,3,4,5,6]. Pure Titanium (CpTi) and Titanium-6 Aluminium-4 Vanadium (Ti-6Al-4V) alloys are the most commonly used materials in surgical medical situations[7], due to their favorable mechanical properties, low cost, corrosion resistance and good tissue tolerance [8]. Both have the disadvantage of the difference between the elastic modulus of the material and bone tissue. Human cortical bone exhibits an approximate value of 20 GPa[1] This difference may result in an inefficient transfer of the load from the implant to the adjacent bone (stress shielding). This phenomenon, observed as a bone resorption around the implant, may result in implant loss and possible bone fracture [3, 4, 9]
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