A comparison of osteoclast resorption pits on bone with titanium and zirconia surfaces

Osteoclasts resorb bone at surfaces, leaving behind pits and trails where both mineral and organic phases of bone have been dissolved. Rough surface structures are deliberately imparted to synthetic implants, in order to improve osseointegration. The aim of this study is to characterize osteoclastic resorption pits on native bone surfaces and to compare these with state-of-the-art titanium and zirconia implant surfaces. The size (i.e. length, width and depth) of resorption pits was compared to the size of surface features of sandblasted and etched titanium and zirconia surfaces. It was found that resorption pits from native bone and surface features of the sandblasted and etched titanium and zirconia surfaces were quite similar in their dimensions. Most structures showed a length between 5 and 40 μm, a width between 2 and 20 μm and a depth between 1 and 8 μm. Additionally, the wavelength-dependent surface roughness was measured, revealing an Sa value of 60 nm in the resorption pits, 86 nm on zirconia and between 127 and 140 nm on titanium surfaces. The results of this study may provide some insight into structural requirements for the bone-remodeling cycle and help to improve the design of new implant surfaces for osseointegration applications.