Abstract:

Abstract:Objective To prepare polylactit acid / hydroxyapatite (PLLA/HA) composites by different mass ratios of PLLA and HA,and to investigate its mechanical properties and cytotoxicity to draw the best mass ratio of PLLA and HA,and to explore its feasibility as the root canal of the maxillary primary anterior teeth. Methods HA microspheres were prepared with NH4H2PO4,Ca (CH3COO)2?H2O, and CH3COONH4.PLLA/HA composites were prepared with solution blending and compression molding method.PLLA/HA composites were divided into PLLA,PLLA-3% HA,PLLA-5%HA,PLLA-7%HA,and PLLA-9%HA groups according to different HA mass percentages.The morphology and size of HA were observed by scanning electron microscope(SEM);the phase analysis was characterized by X-ray diffraction (XRD);the product ingredients were analyzed by fourier transform infrared spectroscope (FT-IR);the flexural strength and  elasticity modulus of the composites were tested by universal material tester;MTT method was used to detect the influence of PLLA / HA composites in the relative growth rate(RGR) of L929 cells. Results The  SEM results showed that the diameter of HA  microspheroidals was 1  μm and HA was composed by lamellar crystals,possessing uniform size.HA characteristic peak was observed in the XRD pattern which showed no significant artifact peaks;the strong absorption peaks of PO43－ groups were observed at 565,606,and 1 042 cm-1 by FT-IR spectra.Compared with PLLA group,the flexural strength and elastic modulus in different  PLLA/HA groups were increased significantly (P<0.01),and the meterial in  PLLA-5%HA group reached the maximum flexural strength and elastic modulus (138 MPa,4.6 GPa).The MTT results showed the RGR of cells in PLLA,PLLA-3% HA,PLLA-5% HA,PLLA-7% HA,and PLLA-9% HA groups were all above 93%,and the cytotoxicity levels were 0―1.Conclusion PLLA/HA composite material is expected to become the ideal root canal material of the maxillary primary anterior teeth due to the certain mechanical properties and non-cytotoxicity.

Key words: polylactic acid;hydroxyapatite microspheres;root canal of , maxillary primary anterior teeth;cytotoxicity