An electron microscopic study on the process of acid demineralization of cortical bone

Demineralization has been shown to foster osteoinductive properties of cortical bone grafts, yet little is known about the process of demineralization and how to control it. The purpose of this study was to investigate the process of cortical bone demineralization by using scanning electron microscopy to evaluate how hydrochloric acid demineralizes cortical bone. Results showed that in the demineralization of diaphyseal cortical bone specimens using hydrochloric acid, a uniformly thick circumferential band of demineralized bone matrix surrounds an inner undecalcified bone core as the process of demineralization occurs. The interface between the demineralized and mineralized section of the bone specimens was extremely sharp. This interface between demineralized and undemineralized bone was noted to advance as a reaction front with increasing demineralization which resulted in continuous shrinkage of the inner cortical bone core. This study suggests that cortical bone demineralization can be best described using an advancing reaction front theory, and this explanation can be used for implementation of the concept of controlled demineralization.