Engineering titanium surfaces for improving osteointegration.

摘要

Titanium is one of the most important metallic biomedical materials in clinical applications. One of the key issues for successful application of titanium is the interaction at the interface between the titanium and the bone. The present study focuses on improving the surfaces of titanium to achieve better capability to bond with natural bone (i.e. better osteointegration). The objectives of this work include: (1) Developing microfabrication methods to produce micropatterns on titanium surfaces for promoting osteointegration; (2) Studying the calcium phosphate (Ca-P) formation on the chemical treated titanium surface and elucidating the mechanism of precipitation theoretically; and (3) Evaluating osteoconductivity of engineering titanium surfaces in vitro and in vivo.; Through mask electrochemical micromachining (TMEMM), jet electrochemical micromachining (Jet-EMM) and the confined etchant layer technique (CELT) were attempted to produce micropatterns on titanium surfaces. TMEMM has a high etching rate and good reproducibility and was used to produce micro-hole arrays on Ti plates for in vivo testing.; The driving force and nucleation rate of Ca-P precipitation in simulated body fluid (SBF) were analyzed based on the classical crystallization theory. SBF supersaturation with respect to HA, OCP and DCPD (dicalcium phosphate) was carefully calculated, considering all the association/dissociation reactions of related ion groups in SBF. The analysis indicates that the nucleation rate of OCP is substantially higher than that of HA, while HA is most thermodynamically stable in SBF. DCPD precipitation is thermodynamically impossible in normal SBF, unless calcium and phosphate ion concentrations of SBF increase.; Osteoconduction of Ti6Al4V surfaces under various conditions, including micro-patterned, alkali-treated, micro-patterned plus alkali-treated, and surfaces without any treatment, was evaluated. TMEMM was used to fabricate micro-hole arrays on the titanium alloy surfaces. In vivo experiments confirm the beneficial effect of alkaline treatment on osteoconduction. The results of in vivo experiments also indicate a synergistic effect of the alkaline treatment and the topographic pattern on osteoconduction. (Abstract shortened by UMI.)