Influence of pre-freezing conditions of octacalcium phosphate and collagen composite for reproducible appositional bone formation

Toshiki Yanagisawa, Ayato Yasuda, Ria I. Makkonen, Shinji Kamakura

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


Even though conventionally prepared octacalcium phosphate and collagen composite (OCP/Col) has exhibited excellent bone regeneration and has recently been commercialized for treating bone defects, reproducible appositional bone formation with OCP/Col has never been achieved. The present study investigated whether appositional bone formation could be achieved by altering the density of OCP/Col and applying liquid nitrogen during the preparation of OCP/Col. The prepared OCP/Col disks had eight variations and were divided into categories according to four different type of densities (1.0, 1.3, 1.7, and 2.0) of OCP/Col and two different pre-freezing conditions of gas phase (G group: −80°C) and liquid phase (L group: −196°C). These disks were implanted into subperiosteal pockets in rodent calvaria, five samples per each eight variations. Radiomorphometric analysis was conducted at 4 and 12 weeks after implantation, and histological analysis was conducted at 12 weeks after implantation. OCP/Col samples in the L group tended to retain their height and shape and had enhanced appositional bone formation, whereas OCP/Col samples in the G group tended to lose their height and shape and had limited appositional bone formation. The appositional bone formation increased along with growing density of OCP/Col, and L2.0 demonstrated higher appositional bone formation than other samples. These results suggest that the pre-freezing conditions and densities of OCP/Col affect the appositional bone formation.

Original languageEnglish
Pages (from-to)2827-2834
Number of pages8
JournalJournal of Biomedical Materials Research - Part B Applied Biomaterials
Issue number7
Publication statusPublished - 2020 Oct 1
Externally publishedYes


  • bone augmentation
  • collagen
  • liquid nitrogen
  • multinucleated giant cells
  • octacalcium phosphate

ASJC Scopus subject areas

  • Biomaterials
  • Biomedical Engineering


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