Biodegradation property of beta-tricalcium phosphate-collagen composite in accordance with bone formation: a comparative study with Bio-Oss Collagen® in a rat critical-size defect model.

PURPOSE The objective of this study was to compare osteoconductivity and biodegradation properties of an in-house fabricated beta-tricalcium phosphate (b-TCP)-collagen composite with those of Bio-Oss Collagen® (Osteohealth, Shirley, NY, USA) using a rat calvarial critical-size defect model. MATERIALS AND METHODS b-TCP-collagen composite material was fabricated by mixing b-TCP granules having a particle size of 0.15 to 0.8 mm and 75% porosity, with bovine dermis-derived soluble collagen sponge. The dry weight ratio of b-TCP granules-to-collagen ratios was 4:1. Bio-Oss Collagen or the b-TCP-collagen composite was used to fill a 5.0 mm-diameter calvarial defect in rats. The defects were evaluated by histological and histomorphological analyses of decalcified histological sections with hematoxylin and eosin staining 6 and 10 weeks, respectively, after surgery. RESULTS The defect implanted with the b-TCP composite contained immature bone structures with dense connective tissue in contrast to the abundant fibrous tissue, but no trabecular structure was observed within the defect implanted with Bio-Oss Collagen at 6 weeks postoperatively. Eventually, the defect filled with the b-TCP composite was covered with dense, continuous, mature bone tissue with complete replacement of the graft material. However, in defects filled with Bio-Oss Collagen, only dense connective tissue, containing limited amounts of immature trabecular bone and abundant remnant Bio-Oss particles, was observed. Histomorphological analysis revealed that the b-TCP composite caused greater tissue augmentation with a larger volume of bone tissue observed in the defect and greater bioabsorption of remnant material than Bio-Oss Collagen. CONCLUSION These results indicated that the b-TCP composite has greater osteoconductivity and better biodegradation properties than Bio-Oss Collagen; these properties of the b-TCP-collagen composite complimented bone formation and remodeling.