Bioactive macroporous titanium implants highly interconnected

Abstract

Intervertebral implants should be designed with low load requirements, high friction coefficient and low elastic modulus in order to avoid the stress shielding effect on bone. Furthermore, the presence of a highly interconnected porous structure allows stimulating bone in-growth and enhancing implant-bone fixation. The aim of this study was to obtain bioactive porous titanium implants with highly interconnected pores with a total porosity of approximately 57 %. Porous Titanium implants were produced by powder sintering route using the space holder technique with a binder phase and were then evaluated in an in vivo study. The size of the interconnection diameter between the macropores was about 210 μm in order to guarantee bone in-growth through osteblastic cell penetration. Surface roughness and mechanical properties were analyzed. Stiffness was reduced as a result of the powder sintering technique which allowed the formation of a porous network. Compression and fatigue tests exhibited suitable properties in order to guarantee a proper compromise between mechanical properties and pore interconnectivity. Bioactivity treatment effect in novel sintered porous titanium materials was studied by thermo-chemical treatments and were compared with the same material that had undergone different bioactive treatments. Bioactive thermo-chemical treatment was confirmed by the presence of sodium titanates on the surface of the implants as well as inside the porous network. Raman spectroscopy results suggested that the identified titanate structures would enhance in vivo apatite formation by promoting ion exchange for the apatite formation process. In vivo results demonstrated that the bioactive titanium achieved over 75 % tissue colonization compared to the 40 % value for the untreated titanium.

In vitro and in vivo evaluations of mechanical properties, biocompatibility and osteogenic ability of sintered porous titanium alloy implant

“…The 75% porosity group in our study had an average diameter more than 400 mm, which is considered appropriate to promote cell proliferation. 21,23 Porosity aims to mimic natural bone and can signicantly decrease elastic modulus, 21,24 therefore, it can help to reduce stress shielding between metallic implants and host bone tissue. The ideal porous implants should provide sufficient mechanical strength for stability and sufficient porosity for cell and tissue ingrowth.…”

“…22 Similar inuence of porosity on bone ingrowth has also been reported in porous bioactive Ti implants. 19,23…”

Current trends of the choice and processing of materials for dental implantation

“…Вообще все имплантаты для костной ткани, а не только дентальные изделия должны разрабатываться с учетом необходимости высокого коэффициента трения и низкого модуля упругости, чтобы избежать излишней нагрузки на кость [7]. С применением первых металлических имплантатов появилась проблема, оставшаяся основной до настоящего времени -адгезии между металлом и костной тканью.…”

“…Результаты рамановской спектроскопии подтвердили, что идентифицированные титанатовые соединения in vivo увеличивают формирование апатита, способствуя образованию ионов, необходимых для этого процесса. Кроме того, имплантаты из такого титана срастаются с тканью на площади более чем 75% по сравнению с 40% при имплантации необработанного титана [7]. В связи с недостаточностью информации об особенностях остеоинтеграции имплантатов в зависимости от характера поверхности сравнивали результаты операций по внедрению разных изделий.…”

Photochemical Surface Modification of Titanium Dioxide Nanotube-Coated Surfaces by Ag-Hydroxyapatite Compositions

“…To this end, the literature is pervaded with coating methods designed to resolve a combination of the implant failure modes listed above by developing multifunctional implant modification procedures [2,[28][29][30][31][32][33][34][35][36][37][38][39][40][41][42]. While it is known that modifying the topography of the implant surface on the nanoscale has shown to be effective in terms of increasing osteogenic phenomena and lessening rejection [43], these coatings do not effectively prevent bacterial colonization.…”