Hydroxyapatite cranioplasty: I. Experimental results from a new quick-setting material.

The biophysical characteristics of a new formulation of hydroxyapatite (HA) for craniofacial applications having a rapid set time was evaluated in animals. Using a mature rabbit model, the material was applied in both cranial defects and as a geometrically shaped cranial onlay. Visual and histological assessment was done after 1 year of implantation. The material remained morphologically stable after 1 year, with complete preservation of its onlay shape and stable fill of the cranial defects. A significant osteoconductive response was seen with bone growth across the inner and outer surfaces of the inlays and along the sides of the onlays. No fibrovascular ingrowth or bony replacement of the material itself was evident as a result of the age of the study animals or the compact density of the material. This rapid-setting HA formulation offers similar favorable tissue responses as those of other longer setting HA materials.