Study of the electrochemical behaviour of Ti osteosynthesis plates used in maxillofacial surgery

Electrochemical behaviour of Ti discs with different pre-treatments (grinding, polishing, anodic and thermal oxidation) and Ti/TiO2 osteosynthesis plates (manufactured and implanted in patients for various time) have been compared in electrolyte containing KCl and NaCl.The XRD measurements showed that the anodically and thermally grown oxide layers on the surface of the implants are built up from poly-crystalline TiO2 anatase. The possible morphological modification – in vitro and in vivo – of the Ti/TiO2 layer was investigated by SEM. Cyclic voltammetric measurements indicated, that TiO2 layer is compact and due to the decreased electrochemical activity of the bulk metal, the Ti/TiO2 samples act like inert electrodes. It was found that the interaction of the implants with the human body and the implantation of the osteosynthesis plates caused minor local damages in the oxide layer. Repassivation of these active sites has been detected by CV and EIS measurements.