The effect of discrete calcium phosphate nanocrystals on bone-bonding to titanium surfaces

We sought to address the question: Can metallic surfaces be rendered bone-bonding? We employed dual acid-etched (DAE) commercially pure titanium (cpTi) and titanium alloy (Ti6A14V) custom-made rectangular coupons (1.3 mm x 2.5 mm x 4 mm) with, or without, further modification by the discrete crystalline deposition (DCD) of calcium phosphate (CAP) nanocrystals. A total of 48 implants comprising four groups were placed bilaterally in the distal femur of male Wistar rats for 9 days. After harvesting, the bone immediately proximal and distal to the implant was removed, resulting in a test sample comprising the implant with two attached cortical arches. The latter were distracted at 30 mm/min, in an Instron (TM) machine; and the disruption force was recorded. Results showed that alloy samples exhibited greater disruption forces than cpTi, and that DCD samples had statistically significantly greater average disruption forces than non-DCD samples. The bone-bonding phenomenon was visually evident by fracture of the cortical arches and an intact bone/implant interface. Field emission scanning electron microscopy showed the bone/implant interface was occupied by a bony cement line matrix that was interlocked with the surface topographical features of the implant. We conclude that titanium implant surfaces can be rendered bone-bonding by an increase in the complexity of the surface topography. (c) 2007 Published by Elsevier Ltd.