The fate of hydroxyapatite cement used for cranial contouring: histological evaluation of a case.

Craniofacial contouring is a commonly performed procedure applied for traumatic and postsurgical cranial vault or facial skeleton irregularities. Hydroxyapatite cement is an alloplastic material composed of tetracalcium phospate and dicalcium phospate anhydrous that transforms into a paste-like substance when these two compounds placed in an aqueous environment. This mixture, which is a nonceramic microporous calcium phosphate combination, is another alternative for refining the craniofacial contour. There are not enough data regarding bone formation within this material after its use in human beings, however. A case requiring secondary craniofacial contouring after a motor vehicle accident is presented. Hydroxyapatite cement was used for reconstruction, and a second look was carried out for further correction during which secondary contouring of the cement was made and a sample of the previously implanted material was histologically evaluated. It was observed in this case that hydroxyapatite cement is incorporated within the surrounding bony structures and permits secondary contouring procedures. New bone and vessel formation was also detected within the implanted material, but this was limited and thus was not convincing for significant osteoconversion as seen in animal studies.