Formation And Detection of Titanium Nano-particles as a Consequence of Wear. An Ex Vivo Study in Human Donor Bone

Summary & Conclusion: This unpretentious investigation actually shows that wear of titanium can occur in human bone simply due to implant insertion. Though wear is extremely limited in human donor bone and of little clinical relevance, further long-term investigations regarding aspects of bio-tribocorrosion in dental implants are needed. The risk of prolonged inflammation during osseointegration is considered to be extremely low, and therefore titanium implants are a safe and predictable therapeutic option. This investigation was financially supported by DGZMK, the Oral Reconstruction Foundation, and Thommen. Introduction: In orthopaedics, wear of titanium endo-prosthesis components is an increasing problem, especially in hip prostheses. Inflammation and tissue degeneration make surgical revisions risky and unfavourable. As approximately one million dental implants are inserted every year in Germany alone, side-effects like multi-etiological peri-implantitis or titanium incompatibility have become more frequent. This study was motivated by the need to prevent disturbance of osseointegrative healing of implants after insertion due to phagocytosis of nano-particles, which may cause activation of prolonged tissue inflammation with a subsequent higher risk of implant loss or activation of multi-etiological peri-implantitis. Methods: Human donor bone of D1 quality (Os femoris) was cut to appropriate size and 6 Conelog implants (Camlog) of 3.8mm diameter (3 implants of osseointegrative surface and 3 of smooth surface, Figure 3) together with 6 Thommen implants of 4mm diameter (3 implants of osseointegrative surface and 3 of smooth surface, Figure 2) were inserted with a maximum torque of 20Ncm. Afterwards, the bone cavity was opened and investigated for titanium wear. Scanning electron microscopy and energy dispersive X-ray spectroscopy were used to detect nano-particles. Statistical analysis was performed using ANOVA. Results: The occurrence of titanium was very limited. Therefore, the size of particles could not be measured. Overall, 150 sites in 12 implants were analysed (average of 12.5 sites per implant). In total, the measurements of 37 sites produced positive detection of small traces of titanium (0.016 – 0.364 wt.%). No differences were found regarding the surface morphology or type of manufacturer, but remarkably there were differences in the sub-groups (Figure 4). There was a statistically significant difference between smooth and osseointegrative surface in Camlog implants (p=0.0161) as well as a marginal significance between smooth surface implants of Thommen and Camlog (p=0.0826). No difference was found in smooth and osseointegrative Thommen implants (p=0.696). Keywords: titanium, nano-particles, human donor bone, Camlog, Thommen