Theory for calcium-phosphate crystal formation in tissue from scanning electron microscope data.

Abstract

Scanning electron microscope (SEM) morphological analysis combined with energy dispersive characteristic x-ray analysis provides insight into the mechanism of biological mineralization. A time series of tissue micrographs and mineralization measurements can permit the determination of the mineralization kinetic behavior and is the basis upon which a computer model has been devised. The computer model is constructed from fundamental principles of crystal nucleation and precipitation theory. Various general forms of the model are tested against the laboratory data for goodness-of-fit using the least squares method, and two models are found to be acceptable. Both of the acceptable models involve inhibition of the mineralization process which has a reaction order ranging from one to two. A third model involving constant nucleation rate must be rejected. Having established working first principle models for the mineralization process, one can compute a constant number of nucleation sites and a supersaturation value for calcium in various mineralized tissues such as the spongiosa and fibrosa of heart valve leaflet implants. These quantities are determined and used in discussing a general theory for biomineralization which emphasizes therapeutic considerations.