Formation of apatite on porous titanium in different supersaturated calcification solution

Apatite coatings were formed on porous titanium surfaces subjected to NaOH aqueous solution by immersion in various supersaturated calcification solutions. The coatings formed in Simulated Body Fluid (SBF) were island-like apatite, while those formed in Supersaturated Calcium-Phosphate Solution (SCS) and Accelerated Calcification Solution (ACS) were plate-like apatite containing OCP (Octacalcium phosphate); all the coatings were calcium-deficient apatite. Increasing the solution supersaturating degree (S) can induce the earlier and quicker apatite nucleation and growth. Small crystals and thin apatite layer were formed in SBF because of the lower 5 and Mg²⁺ ions, which could affect the growing rate of apatite crystal by stabilizing amorphous Ca-P phases, and the coating did not damage the porous structure of the samples. The thickness of the coatings formed in SCS was about 70 μm and greatly reduced the size of the pores of the porous titanium. The coatings formed in ACS would block up the pores.