[Experimental development of a chitosan-bonded hydroxyapatite bone filling paste].

Abstract

Chitosan, a naturally occurring high molecule or weight polymer which is stable in vivo like collagen, has proved a useful biomaterial in applications such as suture thread and artificial skin. A hydroxyapatite bone-filling material was developed with chitosan sol as a binder. Measurements were made of the solubility of chitosan, and of the setting time, compressive strength, and pH value of the material. X-ray microanalysis and diffraction analysis of the material were also conducted. Chitosan is freely soluble in malic acid and succinic acid, but insoluble in citric acid and oxalic acid. The setting time of the bone-filling material tended to decrease with increase in the amounts of its CaO and ZnO components. The setting time increased with increasing ratio of sol to other (powdered) ingredients. The pH value decreased with increasing ratios of chitosan sol to the powdered ingredients. High pH values resulted from increases in both CaO and ZnO. The time between the preparation of the chitosan sol and the onset of kneading significantly affected the compressive strength of the material when set. The strength measured roughly 50% more for times between 90 and 150 minutes than for times shorter or longer than that range. Greater compressive strength was generally observed for increases in both CaO and ZnO. The results of the X-ray microanalysis of the hardened paste showed calcium crystals other than hydroxyapatite.