Effect of particle size on osteoinductive potential of microstructured biphasic calcium phosphate ceramic.

Material factors such as chemistry, surface microstructure and geometry have shown their influence on osteoinduction of calcium phosphate ceramics. Hereby we report that osteoinduction of a micro-structured biphasic calcium phosphate ceramic (BCP) has a relation with the particle sizes. BCP particles with the size of 212-300 mu m, 106-212 mu m, 45-106 mu m, and smaller than 45 mu m were prepared and implanted in paraspinal muscle of dogs for 12 weeks. Histological evaluation of the explants showed abundant bone in all samples with particle size of 212-300 mu m, 106-212 mu m, and 45-106 mu m, while no bone was seen in any sample having particle size smaller than 45 mu m. Bone was formed as early as 3 weeks after implantation in implants having BCP particles bigger than 45 mu m and the volume of the formed bone was similar among the implants with particles larger than 45 mu m after 12 weeks implantation. The results herein show that a size limitation of microstructured calcium phosphate ceramic particles for osteoinduction. It is most likely that the particle size affect inductive bone formation via macroporous structures for body fluid infiltration, cell/tissue ingrowth and angiogenesis. (c) 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 1919-1929, 2015.