Scanning Microscopy
Article Title
Abstract
The chemical and structural properties of hydrolyzed octacalcium phosphate (OCP) appear to be of high relevance to tooth, bone and pathological bioapatites. Hydrolysis of synthetic well-crystallized OCP was studied at constant pH by using the pH stat method over the 6.1 to 8.6 range at 50°C and to a lesser extent at 37°C. Hydrolytic transformation proceeds according to thermodynamic requirements except for some retardation at the highest pH value as a consequence of decreased solubility of OCP which may be rate determining. The product of hydrolysis, OCP-hydrolyzate (OCPH), was characterized by chemical analysis, scanning electron microscopy, x-ray diffraction, electron microprobe (x-ray microanalysis, EDX) and solubility measurements under static and dynamic conditions. Even after prolonged hydrolysis at 50°C, the resulting product was a "calcium deficient apatite" with chemical composition and thermodynamic solubility properties differing from those of well-crystallized hydroxyapatite. Our overall findings provide new evidence that OCP may be a precursor phase in the formation of pathologic calcified deposits and normal biomineral, which appear to be complex hydrolyzates of OCP.
Recommended Citation
Tomazic, B. B.; Tung, M. S.; Gregory, T. M.; and Brown, W. E.
(1989)
"Mechanism of Hydrolysis of Octacalcium Phosphate,"
Scanning Microscopy: Vol. 3
:
No.
1
, Article 15.
Available at:
https://digitalcommons.usu.edu/microscopy/vol3/iss1/15