Low-temperature particulate calcium phosphates for bone regeneration.

ABSTRACT

BACKGROUND: Low-temperature synthesized calcium phosphates are produced by mixing calcium phosphate powders in an aqueous solution resulting in a precipitated phase. These compounds can be formulated in several forms (e.g. injectable cements and implantable blocks), and are commonly used as bone substitutes and drug delivery systems for the treatment of bone defects. As bone substitutes, calcium phosphates in general offer the advantages of being biocompatible and osteoconductive. AIMS: The present work employed a machine-based process to derive a reproducible preparation method for low-temperature calcium phosphate particulate (LTCP). The in vivo outcomes of LTCP were compared with those of three commercially available bone substitutes by histomorphometric measurements of bone formation and material degradation in a rat femur implantation model. MATERIALS & METHODS: Specifically, LTCP, anorganic bovine bone (AB), bioactive glass (BG), and demineralized bone matrix (DBM) were implanted in defects created in the distal aspect of rat femora. Reparative bone and particulate volumes of these biomaterials were evaluated post-operatively using micro-computed tomography and histological analyses at 3, 6, 12, and 16 weeks. RESULTS & DISCUSSION: Results showed that, despite invoking bone formation, AB, BG, and DBM were found un-resorbed in situ at 16 weeks. Conversely, LTCP showed an early increase in bone formation as well as clear evidence of complete degradation and reparative bone remodelling, resulting in the total reconstitution of the marrow cavity and marrow tissue. CONCLUSION: LTCP promoted increased early bone formation, associated with an improved degradation rate, compared with the other three bone-substitute biomaterials tested.