Abstract
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' 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.
