In vitro resorption of three apatite cements with osteoclasts.

To evaluate the replacement of apatite cement (AC) with bone, osteoclasts were incubated for 48 h on the surface of three AC types: conventional AC (c-AC), fast-setting AC (fs-AC), and anti-washout AC (aw-AC), using sintered apatite (AP) and cortical bone as control materials. We found osteoclasts attached to the surface of AC and osteoclastic resorption pits after 48 h of incubation for all experimental AC types. In contrast, no resorption pit was observed on the surface of sintered AP although osteoclasts were attached to the surface of sintered AP. There was no significant difference among the types of AC with respect to the resorption area, but the resorption areas were only approximately 1% of that on the surface of cortical bone. We concluded, therefore, that ACs could be replaced with bone regardless of the type but that it takes extensive time for the ACs to be completely replaced with bone.