Experimental Study On Mineralization Of Hydroxyapatite Crystals Induced By Phosphate Dentin Adhesive

There are many hidden dangers in the present treatment of dental caries and defects,which may cause hypersensitivity, secondary caries and other symptoms, and there is still a problem to be resolved,adhesives and dental organizations are still have marginal microleakage. Rapid progress in biomimetic materials science has brought new ideas to the treatment of dental disease that if biological materials similar to dental hard tissue structure can be biomimetic synthesized which can guide the damage dental tissue repaired themselves, then the above problems will be completely resolved.Objective:This study is based on biomineralization theory that organic molecules regulate and control inorganic crystal growth.The dental adhesive light-cured on glass slide and dentin was used as the organic polymer molecules template, through intake calcium and phosphorus in plasma from simulated body fluid, and the mineralization of hydroxyapatite (HAP) crystals was induced..And the capacity of generating HAP crystals by intake of calcium and phosphorus in simulated body fluid is compared between adhesives containing and without phosphate, in order to provide a basis for repairing dental hard tissue with bonding and biomimetic mineralization.Methods:Firstly, CLEARFIL S3 BOND and3M Adper Single Bond 2 two kinds of adhesive is coated to the glass slide respectively, and then immersed in simulated body fluid(SBF)after light-curing,then incubated for 7days in 37℃constant temperature water bath and SBF is changed once a day. Morphology is observed by scanning electron microscopy(SEM); X-ray diffraction(XRD) and Fourier transform infrared spectrometer (FTIR) respectively, to determine the nature and composition.Then, HAP on dentin is observed with the same method, morphology of the product is observed with SEM, the elemental composition is measured by EDS. Finally ability to induce mineralization of HAP by two adhesive is evaluated and formation mechanisms and influencing factors is analyzed. Results:The results showed that white opaque material is appeared on both two adhesives surface after mineralization; The crystal products of the adhesive containing phosphate mineraled after7days have a diameter of about 1～2μm, were clustered, globular; the characteristic peaks of hydroxyapatite crystals is observed by XRD; the vibration absorption peak of PO43+ and CO32+ is showed after mineralization by FTIR;it's all said that CLEARFIL S3BOND can be induced to be HAP crystals in SBF, but 3M Adper Single Bond 2 doesn't have these results.There also have white opaque material generation on the dentin speciments of the two adhesives which mineralized 7days; The crystal products'diameter are about 10μm by scanning electron microscopy(SEM); HAP with a variety of ion was showed by Energy dispersive spectrometer (EDS);But the 3M Adper Single Bond 2 did not observe formation of HAP crystals.Conclusion:HAP crystals can be induced to minerralize in simulated body fluid.as the dental adhesive with phosphate for the template, this provides a new theoretical basis.for biomimetic mineralization of tooth-like HAP.