Reinforcement with bioresorbable polymer such as PLGA is one of the useful ways to improve the mechanical property of brittle carbonate apatite (CO 3 Ap) foam. In the present study, CO 3 Ap foam was reinforced with various concentrations of PLGA solution (5, 10, 15 and 20 wt%) using vacuum infiltration method and its influence on structure, porosity and mechanical property was investigated. It was found that the amount of PLGA inside the hollow space of the CO 3 Ap foam strut increased with the concentration of PLGA. Porosity likewise was significantly (p<0.05) reduced from 94% (CO 3 Ap foam without PLGA) down to 82% (CO 3 Ap foam reinforced with 20 wt% PLGA). Compressive strength of CO 3 Ap foam significantly (p<0.05) increased from 0.02 MPa (CO 3 Ap foam without PLGA) up to 1.5 MPa (CO 3 Ap foam reinforced with 20 wt% PLGA).

The purpose of this study was to improve the mechanical property of brittle carbonate apatite (CO 3 Ap) foam aimed as bone substitute material by reinforcement with poly(DL-lactide-co-glycolide) (PLGA). The CO 3 Ap foam was reinforced with PLGA by immersion and vacuum infiltration methods. Compressive strength of CO 3 Ap foam (12.0 ± 4.9 kPa) increased after PLGA reinforcement by immersion (187.6 ± 57.6 kPa) or vacuum infiltration (407.0 ± 111.4 kPa). Scanning electron microscopic (SEM) observation showed a gapless PLGA and CO 3 Ap foam interface and larger amount of PLGA inside the hollow space of the strut when vacuum infiltration method was employed. In contrast a gap was observed at the PLGA and CO 3 Ap foam interface and less amount of PLGA inside the hollow space of the strut when immersion method was employed. Strong PLGA-CO 3 Ap foam interface and larger amount of PLGA inside the hollow space of the strut is therefore the key to higher mechanical property obtained for CO 3 Ap foam when vacuum infiltration was employed for PLGA reinforcement.

Carbonate apatite (CO3Ap) foam with interconnecting porous structure is a potential candidate as bone substitute material owing to its similarity to the cancellous bone with respect to composition, morphology and osteoclastic degradation. However, it is brittle and difficult to handle. This is thought to be caused by no organic material in the CO3Ap foam. The aim of this study is to reinforce the CO3Ap foam with poly (DL-lactide-co-glycolide) (PLGA). Immersion and vacuum infiltration methods were compared as reinforcing methods. Compressive strength of unreinforced CO3Ap foam, (12.0 ± 4.9 kPa) increased after PLGA reinforcement by immersion (187.6 ± 57.6 kPa) or by vacuum infiltration (407 ± 111.4 kPa). Scanning electron microscopy (SEM) showed the preservation of full interconnecting porous structure of CO3Ap foam after PLGA reinforcement using immersion or vacuum infiltration. Interface between the PLGA and CO3Ap foam, however revealed that no gap was found between the PLGA and CO3Ap foam interface when vacuum was used to reinforce the PLGA whereas a gap was found when simple immersion was used. Strong interface between PLGA and CO3Ap foam is therefore thought to be the key for higher compressive strength. In conclusion, vacuum infiltration is a more efficient method to reinforce the CO3Ap foam with PLGA for improving the mechanical strength without sacrificing the cancellous bone-type morphology.

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