Effect of Chemical Composition, Surface Shape and Solubility Behavior of Hydroxyapatite (HAP) on the Osteoconductivity and Biocompatibility

Evaluation in vivo and in vitro Study

Abstract

This paper describes the effects of the chemical composition, surface shape and solubility behavior of hydroxyapatite ceramics (HAP) on the osteoconductivity and biocompatibility both in vivo and in vitro study, for the purpose of elucidating the characteristics of HAP as an ideal artificial material.
At first, the osteoconductivity of HAP was studied histologically with 6 types of HAPcylinder, and their solubility in an isotonic NaC1 solution was also examined. The results showed that a HAP-cylinder with lower relative density and higher solubility had an excellent osteoconductivity. The content of β-TCP, however, did not influence the initial osteoconduction.
Secondary, the biocompatibility and solubility of 6 types of HAP-plate were studied with tissue culture methods. Consequently, in the culture solution, the solubility of inorganic composition differed from each other, and these differences influenced the biocompatibility. However, a HAP-plate with lower relative density and irregular surface showed a good initial attachment to the culture cells.
The last experiment by granfting HAP-granules into the subcutaneous tissue revealed that HAP with lower relative density had a poor biocompativility. The reason was thought to be that such a HAP may have a high much solubility of inorganic composition.