Use of hydroxyapatite cement to support implants in extraction sockets.

Bioactive cements based on calcium phosphate chemistry have been developed to serve as bone substitute materials. One such commercial product, BoneSource, is a hydroxyapatite cement (HAC) used for small bone defects in the craniofacial complex. We have investigated the possibility that HAC could be used to support bone growth adjacent to dental implants placed in immediate tooth extraction sites. Variable levels of bone contact were noted up to 3 months postimplantation. Considerable loss of HAC occurred and was thought to be because of "washout" of the cement before complete cement setting. When HAC was immobile in the surgical site, the bioactive nature of the cement led to HAC resorption and bone deposition. Efforts to maintain the HAC in situ should be expanded so that the full clinical potential of the HAC can be realized.