Initial cell adhesion of MC3T3-E1 osteoblast-like cells to HAP, HAP—30% PA, and HAP—30% PA—12 h at 0.5 and 24 hours. At 0.5 hours, the number of cells adherent to HAP—30% PA—12 h was significantly greater than that for HAP (). At 24 hours, the number of cells adherent to HAP—30% PA—12 h was significantly greater than those for both HAP () and HAP—30% PA ().