Surface analysis of failed oral titanium implants

The aim of the present study was to investigate the surface topography, composition, and oxide thickness of consecutively failed, oral Brånemark implants in order to determine possible causes for failure. The failure criterion was lack of osseointegration manifested as implant mobility. Ten implants were retrieved before loading (early failures) and 12 during a period of function up to 8 years (late failures). At retrieval, early losses did not display any clinical sign of infection. All late failures were radiographically characterized by peri-implant radiolucency and did not show infectious signs with one exception. No implant seemed to be lost due to peri-implantitis (plaque-induced progressive marginal bone loss). Twelve implants were analyzed by scanning electron microscopy (SEM), Auger electron spectroscopy (AES), and depth profiling using a blind protocol. Two pristine fixtures, which underwent the same preparation as the failed implants, were used as controls. In the SEM, control samples were essentially free from macroscopic contamination, whereas failed implants contained varying amounts of tissue residues. AES showed that all surfaces consisted of Ti oxide and varying amounts of additional elements, with C dominating in most cases. Nitrogen and sometimes Na, Ca, P, Cl, S, and Si were detected. The Si contamination was most likely due to ion leaching from the glass vials used for storage. Depth profiles showed a typical oxide thickness of 5-8 nm for all samples. In conclusion, no significant changes in the oxide layer composition or thickness as a result of implantation were observed. The results do not indicate any material-related cause for the failures of these implants. Possible reasons for these failures were impaired healing, asymptomatic infection, and overload.