Contrast-enhanced X-ray microtomography of the bone structure adjacent to oral implants

One of the most important aims about cortical and cancellous bone research is to understand the factors that determine their mechanical properties, how these properties are maintained, and how bone reacts to changes in its environment, such as the introduction of a titanium implant. Trabecular morphometry has been traditionally assessed in two dimensions, where the structural parameters are either inspected visually or measured from sections, and the third dimension is added on the basis of stereology. Particularly, limiting is the destructive nature of this extremely time consuming procedure, preventing the specimens from being used for other measurements. The most common technique used to overcome some of the limitations of two-dimensional analysis is stereo- or scanning microscopy to assess three-dimensional structural indices qualitatively. Synchrotron radiation X-ray computed microtomography is a particular kind of X-ray computerized axial tomography with higher resolution and the possibility to choose among a very wide range of X-ray energies. Beam energies ranging between 30 and 40 keV will provide a satisfactory signal-to-noise ratio and contrast for bone, except for the parts falling in the shadow of the Ti implant. Higher beam energies would provide correctly exposed images, with lower -to noise ratio for the bone trabecular structure. We will show how the use of alternative materials, such as aluminum, while not altering the evaluation of the mechanical impact of an implant, allows a satisfactory non-destructive, three-dimensional analysis of the bone-implant interface.