Evaluation of Alkali Treatment for Porous Titanium as Bone Reconstruction Material

Objectives: Porous titanium fabricated by resin-impregnated titanium substitute technique has good mechanical strength and osteoconduction. Alkali treatment for titanium surface creates bioactive surface. Alkali treated porous titanium is expected to accelerate bone formation. The purpose of this study was to evaluate bone reconstruction ability of alkali treated porous titanium.
Methods: Porous titanium (85% porosity) were treated with alkali solution (5N NaOH, 24 h). To assess material properties, we analyzed surface structure by scanning electron microscopy (SEM), and mechanical strength. To assess bioactivity, each sample was soaked in simulated body fluid (SBF) for 7 days. Surface observations, weight change ratio measurement (after/before soaked SBF) and surface elemental analysis were performed. We also designed in vivo study with rabbit femurs. After 2 and 3 weeks implantation, histological observation and histomorphometric bone formation ratio analysis were performed. All data were statistically analyzed Student’s t test (p < 0.05).
(Approved by Hiroshima University animal experiment ethics committee: A11-5-5)
Results: Non-treated porous titanium (control) appeared smooth surface and alkali treated porous titanium (ATPT) had nano-size needle-like rough surface. ATPT had similar mechanical strength as control. After soaking into SBF, we observed apatite-like crystals in SEM image, weight gain, and high Ca and P in ATPT. There was much bone formation at early stage in ATPT compared with control.
Conclusions: It was suggested that alkali treated porous titanium has a bioactive surface and induce bone reconstruction effectively. This novel bioactive porous titanium could expect to be a good bone reconstruction material.