Study of interface phenomena between bone and titanium and alumina surfaces in the case of monolithic and composite dental implants.

The interface between mandibular bone and dental implants was examined with the in vivo dog model. Implant/bone interfaces were investigated for three types of materials: Ti-30 wt% Ta/Al2O3, titanium and Al2O3 using microscopy techniques covering a large magnification range: scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray analysis and Auger spectroscopy. During the interaction of the Al2O3 ceramic with bone, an interfacial layer about 15 microm thick is formed. The same phenomenon was observed at the titanium bone interface, where the thickness of the layer was about 10 microm. In all cases, interface layers were sharp with well-defined borders between bone tissue and implant materials. No calcification took place inside the interface layer. A chemical analysis performed on this layer shows the presence of titanium, calcium and phosphorus in the case of titanium implants, and aluminium, calcium and phosphorus in the case of alumina implants. A rapid decrease in metal composition with increasing distances from the implant surface is correlated to a slow increase in calcium and phosphorus in the direction of the bone. Direct contact between implant and bone was observed. No biocorrosive effects were detected at the Ti-30 wt% Ta/Al2O3 metal-ceramic interface.