Materials science could improve the lives of people unknowingly suffering from hyperglycaemia - raised blood sugar levels. Hyperglycaemia is the most well-known sign of a group of metabolic disorders commonly referred to as diabetes mellitus. One of the problems associated with undiagnosed hyperglycaemia is an increased risk of dental implant failure; thought to be caused by compromised growth of new bone. There are other putative mechanisms by which implants might fail in hyperglycaemia patients. Now, researchers at the University of Toronto have investigated how modifying the topography of the implant surface at the nanoscopic level might be exploited to improve osteoconduction and accelerate bone healing [E. Ajami et al, Acta Biomaterialia, doi:10.1016/j.actbio.2013.09.020].
The team carried out two experiments in parallel: the first osteotomy model tracked bone healing in laboratory rats with different blood sugar profiles using standard biological analyses. In the second they looked at how the micro-topography or nano-topography of implant surfaces affected bone growth around them using back scattering electron imaging. Surfaces were acid etched using cocktails of hydrofluoric, sulfuric and hydrochloric acids. Surface roughness was measured using optical interferometry. The micro surfaces had 1-3 micrometer pits and peaks produced by the acid etching; while the nano surfaces had nanoscopic pits within the micrometer pits.
Fundamentally, raised blood sugar was indeed responsible for poor bone healing rates as demonstrated in the osteotomy model; while the implant study demonstrated that nanoscopic surface features on their titanium model implants promoted bone growth much more effectively than did the micro surfaces. The team points out that studies with a fluorescence probe also revealed otherwise hidden details about the degree to which reparative bone was mineralized at different stages in the experiment. The animals with hyperglycaemia displayed retarded mineralization.
The research lends weight to the hypothesis that hyperglycaemia can inhibit bone healing and so could have implications for dental patients with undiagnosed hyperglycaemia. Moreover, unexplained loss of dental implants or the failure of bone healing following a fracture in an undiagnosed patient might be indicative of latent hyperglycaemia and should warrant further investigation in such a patient. The team points out that not all controversy has been addressed in that hyperglycaemia is also associated with blood-clotting problems and that these can interfere with bone healing too.
David Bradley
David Bradley blogs at http://www.sciencebase.com and tweets @sciencebase, he is author of the popular science book "Deceived Wisdom".
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