Preparation Of Potassium Doped Carbonate Nano Hydroxyapatite And Research Of Its Effect Of Sealing Dentin Tubules

Purpose:Dentin hypersensitivity is a common clinical symptom, especially on vitalpulp for tooth repair, dentin sensitivity is inevitable.The mechanism of dentinsensitivity is not yet clear,fluid dynamics theory has been widely accepted byresearchers. Currently,the kinds of desensitizers are varid on clinical, the mechanismsare not the same,and nano hydroxyapatite with the similarity to human hard tissuesand its excellent biocompatibility and biological activity has been paid more and moreattention.In this paper, we synthetized a carbonate hydroxyapatite nanoparticlescontaining potassium,and used it as a desensitizer.Its composition and properties areanalyzed by XRD, FT-IR,TEM,Ca/P ratio test, BET and other methods.Then coated iton the surface of dentin and evaluated its effect of sealing dentinal tubules byscanning electron microscope.Methods：Carbonate nano hydroxyapatite and potassium doped carbonate nanohydroxyapatite are prepared by chemical precipitation method.The surfacemorphology and properties of the materials were investigated by X-ray diffraction(XRD), infrared absorption spectra (IR), transmission electron microscopy(TEM)andenergy DispersiveSpectrometer (EDS). Surface area to volume was tested by BET(Brunauer,Emmett,Teller) method.The results were analyzed and compared. Collectcomplete third molars of maxillary with no carious in a month,prepare them intodentin discs.Treat the dentin surface of each group respectively with nanohydroxyapatite, carbonate nano hydroxyapatite, potassium doped carbonate nanohydroxyapatite.Then we observed their effects of sealing dentin tubules and the depthof entering dentin tubules by scanning electron microscope.Results：1.1All the diffraction peaks of standard of nano hydroxyapatite, besidesdiffraction peak of carbonate are found in the XRD results.The pattern shows all the peaks corresponding characteristically to CHAp, showing its structural integrity.1.2In addition to the main peak of phosphate,hydroxyl,the absorption peak ofcarbonate is also fonud in the FTIR results.1.3Energy spectrum analysis of carbonate nano hydroxyapatite shows a peakcorresponding to elements Ca,C,O,P. Peaks of potassium doped carbonate nanohydroxyapatite corresponding to K, Ca, C, O, P.The Ca/P molar ratio are are less than1.67.1.4Through TEM columnar crystal structure was observed.2Specific surface area test results for a sample of2is larger than the sample3,sample size distribution is in nanometer range.3Under the scanning electron microscope, three kinds of materials can effectivelyseal the dentin tubule, potassium carbonate doped nano hydroxyapatite can infiltrateinto the dentin tubules deeper than the residue2groups.Conclusions： The materials synthesised in this experiments confirmed to behydroxyapatite nano carbonate and potassium doped carbonate nano hydroxyapatitethrough the characterization of surface morphology and properties of them. In vitro,carbonate nano hydroxyapatite and potassium carbonate doped nano hydroxyapatitecan seal dentinal tubules,and have a good effect on prevention dentinhypersensitivity,the effect is better than pure nano hydroxyapatite.