Effectiveness of biphasic calcium phosphate block bone substitutes processed using a modified extrusion method in rabbit calvarial defects.
OBJECTIVE
This study evaluated the mechanical and structural properties of biphasic calcium phosphate (BCP) blocks processed using a modified extrusion method, and assessed their in vivo effectiveness using a rabbit calvarial defect model.


METHODS
BCP blocks with three distinct ratios of hydroxyapatite (HA):tricalcium phosphate (TCP) were produced using a modified extrusion method:HA8 (8%:92%), HA48 (48%:52%), and HA80 (80%:20%). The blocks were examined using scanning electron microscopy, X-ray diffractometry, and a universal test machine. Four circular defects 8 mm in diameter were made in 12 rabbits. One defect in each animal served as a control, and the other three defects received the BCP blocks. The rabbits were sacrificed at either two weeks (n=6) or eight weeks (n=6) postoperatively.


RESULTS
The pore size, porosity, and compressive strength of the three types of bone block were 140-170 µm, >70%, and 4-9 MPa, respectively. Histologic and histomorphometric observations revealed that the augmented space was well maintained, but limited bone formation was observed around the defect base and defect margins. No significant differences were found in the amount of new bone formation, graft material resorption, or bone infiltration among the three types of BCP block at either of the postoperative healing points.


CONCLUSIONS
Block bone substitutes with three distinct compositions (i.e., HA:TCP ratios) processed by a modified extrusion method exhibited limited osteoconductive potency, but excellent space-maintaining capability. Further investigations are required to improve the processing method.
Department of Periodontology, Kyung Hee University School of Dentistry, Seoul, Korea.
Hyun-Chang
0000-0001-7695-1708
HC
Lim
Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, Seoul, Korea.
Kyung-Ho
0000-0002-7477-6982
KH
Song
Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, Seoul, Korea.
Hoon
0000-0002-8582-0862
H
You
Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, Seoul, Korea.
Jung-Seok
0000-0003-1276-5978
JS
Lee
Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, Seoul, Korea.
Ui-Won
0000-0001-6371-4172
UW
Jung
School of Materials Science & Engineering, Yeungnam University, Gyeongsan, Korea.
Suk-Young
0000-0002-1382-2041
SY
Kim
Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, Seoul, Korea.
Seong-Ho
0000-0001-6704-6124
SH
Choi
Bone regeneration; Bone substitute; Calcium phosphate