| Summary: | 碩士 === 台北醫學院 === 醫學研究所 === 90 === The purpose of this study was to investigate tissue responses of porous poly(L-lactide) (PLLA)/ hydroxyapatite (HA) composites as biodegradable materials. The porous HA was obtained by mixing HA with the same amounts of sucrose as binder and salt as filler, pressing the mixure under 39 kgf/cm2 for 5 minutes, melting the sucrose at 220 C and sintering under 1345C for 10 hours then. The obtained porous HA was immersed into graded PLLA solution series[1%, 5%, 10%, 20%] while the used PLLA was prepared via a thermal degradation method. Differential scanning calorimeter, material testing system, X-ray diffractometer were used to measure the physical properties of the composites. In vitro study suggested that PLLA might provide the acid environment to help HA to dissolve.
After sterilization, the composites are implanted into the 2x4x2 mm3 defects on mandible bones of 14 Beagle dogs. Two kinds of implants were used — HA with PLLA and without PLLA. 1, 2, 3, 4, 9, 16, 26 weeks after implantation, the samples were examined histologically by light microscopy. The results showed that new bone formation happened most fast in control groups, then HA-without-PLLA groups, slowest in HA-with-PLLA groups. PLLA/HA may not be good materials for bone grafts but the improved bending strength may be an advantage as implants.
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