Biodegradable beta-tricalcium phosphate disks (TCP) of two configurations were inserted into 15-mm-diameter craniotomy wounds and nontreated control sites were evaluated in 60 rabbits. There were no adverse tissue reactions and no apparent difference in the clinical appearance of the 12and 24-week implanted disks. By 36 weeks and continuing to 48 weeks, the omnidirec-tional TCP (OTCP) implants were degrading more rapidly than the unidirectional TCP (UTCP) implants, with degradation progressing centripetally and replacement by woven bone and maturing lamellar bone. Host-implant interface of both TCP configurations was a bone bond without interposed soft tissue. TCP disks may be clinically useful for craniotomy repair.
Regeneration of bone of the facial skeleton lost as a consequence of trauma, disease, or resective surgery has been a goal sought by oral and maxillofacial surgeons. Although many materials have been used for 0s- seous wound repair, no agent currently available provides the surgeon with a predictable level of bone regeneration. Autogenous grafts and allogeneic implants are the substances most commonly used by surgeons to treat bone defects; unfortunately, these materials have a failure rate ranging from 13-30%. ' Ceramics and polymer alloplastic materials have been reviewed as possible alternatives to the traditionally used autogenous and allogeneic bone preparation^."^ To the best of our knowledge, there have been no studies that evaluated TCP in the form of disks for repairing nonhealing, 15-mm skull defects for a period of 48 weeks. It was the purpose of this study, therefore, to determine if disk forms of unidirectional and omnidirectional, biodegradable tricalcium phosphate (100% beta phase) could be used for treating craniotomies. *The views of the authors do not purport to reflect the position of the Department of the Army or the Department of Defense. (Para. 4-3, AR 360-5).