Biocompatibility Of Polylactic Acid Composites As Root Canal Post In Primary Teeth

Currently, for the widespread teeth crown defect due to dental caries or trauma, it is usually to use the routine root canal therapy. And yet, it is difficult to restore normal appearance because of the lack of enough risistance form and retention form owing to little residual tooth body organization. In regard to using root canal post to restore the crown shape of permanent teeth, think is there a root canal internal fixed device, which restores the normal appearance of crown, does not affect primary teeth replacement of normal permanent teeth and has some biocompatibility?So, our research team put the biodegradable material-Poly-L-lactic Acid with the different mass fraction of hydroxyapatite to prepare PLLA/HA composites by using solution blending and compression moding method. And the composites which selected the mass fraction of HA 5% had the best mechanical properity and were expected to be a kind of ideal materials as root canal post in primary teeth.According to the standard for biological evaluation of medical devices of the People’ s Republic of China, a series of experiments were performed in vivo and in vitro to evaluate the biocompatibility of PLLA/HA composites prepared. We aimed to further explore the feasibility of this material as root canal post in primary teeth so as to provide theoretical basic for clinical application. Under inversion fluorescence microscope, mouse fibroblast line L929 were in fusiform shape, adhered to the composites’ surface and grew well. The leaching liquor of composites could not cause the hemolytic reaction(hemolytic rate 1.19%) and pyrogen reaction in rabbits. The mice injected the leaching liquor of composites were in activity, eating behavior and no death and adverse reaction. The result illustrated the composites were not toxic.The pure PLLA and PLLA/HA composites implanted in rabbits’ muscle caused a mild inflammatory reaction and a thick fiber capsule. The rabbits’ muscle only had few inflammatory cells during the early stage. As time went on, the inflammatory reaction was inhibited and the fiber capsule had disappeared.SEM showed that pure PLLA had a compact structure initially. The HA grains on the PLLA/HA composites were evenly distributed and of uniform size, some porous structures and cracks wereobserved gradually. In summary, the PLLA/HA composites had a good biocompatibitity and met the requirement of biological safety.