Journal of Oral Tissue Engineering

Effects of Granule Size and Surface Properties of Red Algae-derived Resorbable Hydroxyapatite on New Bone Formation

Takahiro NAKAMURA1, Makoto SHIOTA1, Hidemichi KIHARA1, Yasuo YAMASHITA2 and Shohei KASUGAI1

1Oral Implantology and Regenerative Dental Medicine,
2Maxillofacial Anatomy, Tokyo Medical and Dental University, Tokyo, Japan

J Oral Tissue Engin 2008;6(3): 167-179

Full Text. DOI

The purpose of this study was to examine the biodegradation and bone replacement of resorbable hydroxyapatite derived from red algae (RHGA) and to investigate the effect of particle size and surface properties on osteogenesis. RHGA particles (300-1000 micrometers), which had a smooth surface, and crushed small RHGA particles (100-300 micrometers), which had a rough surface with open pores, were used.
Calvarial bone defects were created in 30 rats. The defects were filled with blood clot (Group A), original particles (Group B), or small particles (Group C). The animals were sacrificed 4 (n=15) or 8 (n=15) weeks later. The bone was examined histologically and histomorphometrically.
In Group A at 8 weeks, new bone extended towards the defect's center, but the initial thickness was not restored. In Group B, connective tissue encapsulated most particles at 4 weeks; at 8 weeks, some particles collapsed from the originally concave surface, and immature bone was observed around this area. In Group C, new bone and particles occupied most of the defect at 8 weeks. The particlesf pore system lost its septal structure and was invaded by mature bone.
The present results indicate that structural architecture, such as a pore system, appears to be crucial for particle resorption and new bone formation and that small RHGA having rough surface with open pore is potential as bone substitute.

Key words: bone augmentation, resorbable hydroxyapatite, granule size, surface property, bone substitute material