Studies On Biological Activities Of Pure Titanium Dental Implant

Many researchers have been trying to improve the bioactivity of pure titaniumdental implant through various surface modification treatments. So far the SLA(sandblast and acid-etching) technology has been most widely used. In recent years,with the rapid development of MAO (micro-arc oxidation) technology, the refinedceramic layer with uniform porous structure can be built by the MAO, which isregarded as a potential application for improving bioactivity. Therefore, in the presentstudy, the comparative work of the SLA and MAO technologies has been carried out toinvestigate the differences on the improvement for bioactivity of pure titanium dentalimplant.Firstly, the preparation parameter was optimized to obtain the optimal MAOporous ceramic layer, and then the optimized MAO and SLA ceramic layers weresubjected to alkali treatment. Finally, both the kinds of alkalized ceramic layers wereimmersed into SBF for different days. Based on the deposition behavior of apatite onthe MAO and SLA ceramic layer, the investigation was performed to evaluate whichtechnology is better for improving bioactivity, and the mechanism of apatite depositionwas discussed.In details, orthogonal method and formula scoring method were used to optimizethe processing parameters for obtaining the uniform MAO porous ceramic layer, and theoptimal parameter is positive voltage for400V, duty ratio for60%, frequency for550Hz, and oxidation time for25min. The optimized MAO ceramic layer was mainlycomposed of anatase TiO2, containing only O, P and Ti. The SLA ceramic layer withoutporous structure was composed of anatase TiO2, brookite TiO2and other types oftitanium oxides. Besides, the composition of residual emery was also found on thesurface. After alkali treatment, the titanium sol rich with–OH was formed on thesurface of the ceramic layers, due to the good hydrophilic nature of–OH, which makes the ceramic layers possess the moderate wettability and thus be beneficial to osteoblastadhesion.After alkali treatment, the ceramic layers were immediately immersed into SBF.When the time of cultivation is up to14days, the surface of ceramic layers wascompletely covered by bone-like apatite. In this condition, there were no obviousdifferences between the MAO and SLA ceramic layers, both of which possess the goodbioactivity for bone-like apatite deposition. However, the bioactivity of both the MAOand SLA ceramic layers，which preserved for4weeks before culturing in SBF, wassignificantly deteriorated.The surface morphology of ceramic layers and local ion concentration had a greateffect on apatite deposition. Due to the dissolution behavior, the pH value of SBFdecreased first and then increased. However, during the whole process the dissolutionrate was less than the deposition rate, as a result, the surface of ceramic layers could becovered completely by apatite.