PIXE and micro-PIXE studies of ion release around endosseous implants in animals

The so-called ''osseointegration'' of oral and orthopedic implants means that newly-formed bone embeds the alloplastic implant materials allowing long-term clinical success. Commercially pure smooth titanium, rough titanium (sand blasted or plasma spray coated), hydroxylapatite and other coatings present different patterns, especially in the early healing phase after surgery. PIXE and micro-PIXE analysis are to be considered effective techniques to measure ion diffusion at the implant-bone interface, and to evaluate the possible diffusion of metal into the organism. Investigations were carried out in rabbits, both with PIXE and micro-PIXE, to evaluate a possible release of titanium from implants into the tissues and to measure other elements at the bone-implant border. Preliminary results suggest that a minor diffusion of titanium exists, even if probably without any significant clinical disturbance. Indeed, there is some evidence of initial titanium accumulation in some organs after six months. A possible deposition of calcium and phosphorus on the metal might indicate a good biological behavior of titanium.