The purpose of this study was to observe morphologically new bone formation around hydroxyapatite(HA) mixed with PLGA in hole(5.5 mm diameter, 4 mm depth) of rabbit tibia. At 3 day, 1, 2, 4, weeks, experimental animals were sacrified. Removed bones which were containing HA mixed with PLGA were fixed with 10% neutral formalin, dehydrated, and embedded with Spurr low viscosity resin. After the specimen was cut by 500㎛ with slow diamond wheel saw, these were grinded up to 100㎛, examined with light and polarizing microscope. For SEM the resin sections were coated with gold. The obtained results were as follows.
1. Histopathologic features of both group, chronic inflammatory cell infiltration disappeared after 2 weeks, and HA powders were well encapsulated by fibrous tissue at 3 days. After 2 weeks of experimental groups active bone formation was observed around resorbed HA mixed with PLGA, and at 4 weeks, well calcified mosaic like trabecular bone was seen.
2. Polarizing microscopic features of control group, early new bone formation was seen, but there were less calcified bone attached to HA. In experimental group well calcified bone trabecular were seen between the resorbed HAs.
3. In SEM HA was well resorbed in HA mixed with PLGA. New bone with lacunae attached HA was seen, and bony spicules were more scattered.
From aboving results, there were few chronic inflammatory cell infiltration after 2 weeks in both group, while early resorbed HA in experimental group was well encapsulated by fibrous tissue. In early stage of experimental group new bone formation was more delayed, but at 4 weeks well calcified, mosaic like new bone trabecular between HAs were seen.
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