Plasma immersion ion implantation treatment of medical implants

Using oxygen-plasma immersion ion implantation (PIII) into titanium it is possible to form hard, dense and thick rutile layers with excellent biocompatibility in a temperature region down to 200°C. The thickness and crystallite size can be independently adjusted by changing the process temperature and the treatment time. As a first step towards the application for osteosynthesis plates used in jaw surgery, the biocompatibility of rutile surface layers was tested using a rat model, which is well established for biocompatibility testing of metal surfaces. Small rods with a diameter of 0.9 mm and a length of 10 mm, prepared from titanium (grade 2) and two different NiTi alloys (NiTi SE508, NiTi SM496), were implanted with oxygen at temperatures between 200°C and 600°C with an incident dose of 5×1017 O atoms cm−2. Afterwards they were inserted into rat femurs, together with untreated samples as a control group. The results of the animal tests are correlated with the morphology and structure of the treated surfaces.