An in vitro evaluation on the percutaneous sites of MAO-treated implants

Microarc oxidation (MAO) was considered to be one of the most effective surface coating techniques to improve the osseointegration of the implants. However, the influences of such coating on the skin epithelium interface still gained less attention in present literatures. Clinical data showed that 15-20% of patients might have an infection following prosthetic rehabilitation because of the percutaneous problems. Epithelial downgrowth around transcutaneous implants associated with infections can occur due to the inappropriate materials and surface structures of the implants. Aimed at evaluating the biological properties of the percutaneous sites of the MAO-treated titanium implants, the behavior of human skin epithelial cell (HSEC) and the Staphylococcus aureus (S. aureus) on the MAO-treated and the untreated titanium (Un_Ti) surfaces were evaluated using in vitro models. Our results showed that MAO-treated titanium surfaces did not well support the growth, adhesion, and proliferation of HSEC. Additionally, they were much more susceptible to S. aureus when compared with untreated titanium (Un_Ti) surfaces. Analysis of our data, taken together, revealed that MAO-treated titanium surfaces may not be suited for the interfacing devices with human skin epithelium. Un_Ti surfaces showed a more satisfactory biocompatibility to the HSEC, as well as better in the prevention of S. aureus adhesion and multiplication. Therefore, we suggest that MAO treatment on the "percutaneous sites" should be carefully reconsidered in the next generation of MAO-treated implants.