AFM study on the surface dissolution of hydroxyapatite

The surface dissolution of hydroxyapatite ceramics in distilled water was investigated by using atomic force microscopy (AFM) and scanning electron microscopy (SEM). The disks made of hydroxyapatite powder were sintered at 1200 degrees C for 2 h in air with under moisture protection. After sintering, the disks were polished to smoothness using 1 mu m diamond and they were soaked in 40 ml of pH 7.4 distilled water at 37 degrees C for certain period of time. The morphological change of hydroxyapatite surface, specifically at the initial stage of immersion, and related surface roughness were observed with immersion time. The present study suggested that an artificial fact like surface scratch in this case initiated to be eliminated prior to the surface dissolution along grain boundary. That is, the surface roughness decreased at the initial stage of immersion, and then increased due to the surface dissolution.