The mechanical properties and solubility of strontium-substituted hydroxyapatite.

The mechanical properties and solubility of sintered Sr-substituted hydroxyapatites were examined in order to investigate the influences of Sr incorporation into hydroxyapatite in bones and teeth on them. Hydroxyapatite (HAp), Sr-substituted hydroxyapatite (Ca.SrAp), and strontium-hydroxyapatite (SrAp) were synthesized and sintered. The bending strength and Young's modulus were measured. Also, solubility in isotonic NaCl solution was examined. The Young's modulus of Sr-substituted hydroxyapatite (Sr wt% = 1.0) and hydroxyapatite surface treated with Sr ion were greater than that of hydroxyapatite. The bending strengths of Sr-substituted hydroxyapatites (Sr/Ca = 4/6 and less) were reduced slightly compared to that of hydroxyapatite. The bending strength of hydroxyapatite surface treated with Sr ion was increased compared to that of hydroxyapatite. The solubility in isotonic NaCl solution at 37 degrees C was increased with an increase in Sr content. The effects of Sr on the mechanical properties and solubility of bones and/or teeth are discussed.