The Basic Research Of Polylactic Acid Composites Prefabricate As Root Canal Post In Primary Teeth

In the past half a century, primary teeth caries treatment center gradually shift from theplucking treatment to reparative therapy. Reparative therapy including filling、inlay andpreformed metal crowns. However, it is necessary that root canal therapy and root canalinternal fixation before the crown restoration of primary teeth which have been severelydamaged. The internal fixation material used in root canal include: metal posts、resin posts、fibre posts and biological posts made from extracted primary teeth. Due to Metal, resin andfiber cannot be absorbed by the body’s tissues, the post mostly located a third in the neck，When used in primary teeth for not affect primary teeth replacement of normal permanentteeth, but it is easily lead to material loss or root fracture etc. Although biological posts madefrom extracted primary teeth can overcome the problem of insufficient implant length androot absorption, it is also exist potential risk such as infection and exclusion. Therefore, it isimportant clinical significance to preparation of root canal post in primary teeth, which has acertain biomechanical properties, good biocompatibility and synchronously degradation whenthe primary teeth root physiological absorption.In this study, HA microspheres were prepared with NH4H2PO4、Ca (CH3COO)2H2O and CH3COONH4. PLLA/HA composites were prepared with solution blending andcompression molding method according to different HA mass percentages0%、3%、5%、7%、9%in composites. To detect physical and chemical properties of HA by scanning electronmicroscopy (SEM)、 X-ray diffraction (XRD) and fourier transform infrared spectroscopy(FT-IR);the flexural strength and elasticity modulus of the composites were tested byuniversal material tester;MTT method was used to detect the effects of PLLA/HAcomposites in the relative growth rate (RGR) of L929cells.Aims to further explore thefeasibility of the composites as the root canal of the maxillary primary teeth, and provide newideas of primary teeth residual root and crown in the clinical treatment of. Results，thediameter of HA microspheroidals was1μm and HA was composed by lamellar crystals, possessing uniform size and crystallinity and high purity. Compared with PLLA group, theflexural strength and elastic modulus in different PLLA/HA groups were in increasesignificantly (p<0.01)，and the meterial in the composite with HA mass percentages5%groupreached the maximum flexural strength and elastic modulus (138MPa、4600MPa). The MTTresults shows the RGR of cells in the composite with HA mass percentages0%、3%、5%、7%、9%groups were all above93%,and the cytotoxicity levels were0-1．Conclusion,PLLA/HA composite material is expected to become the ideal root canal material of themaxillary primary teeth due to the certain mechanical properties and non-cytotoxicity.