In Vitro Study On The Time Correlation Of Bioactive Glass In Promoting Dentin Remineralization

Objectives1.To study the morphological characteristics and phosphate radical changes of partially demineralized dentin surface induced by bioactive glass Aominqing(?)under different action durations,so as to provide further theoretical basis for the clinical application of Aominqing(?)in alleviating dentin sensitivity.2.To study the morphological characteristics and physicochemical properties of the mineralized layer changes of the completely demineralized dentin surface induced by the bioactive glass Aominqing(?)under different action durations,so as to provide theoretical basis for the role of Aominqing(?)in dentin remineralization.MethodsThe freshly isolated human third molars without white spots,caries and cracks were selected to prepare dentin samples with a thickness of about 1 mm.1.According to the random number table method,35 dentin samples were randomly divided into 7 groups(n=5):healthy dentin group,partially demineralized group,group A,group B,group C,group D and blank control group E.Except for the healthy dentin group,all other groups were treated with 0.5M EDTA for 30mins for partial demineralization,and then groups A,B,C and D were treated with Aominqing(?)for 1,4,7 and 14 days respectively,while group E was only placed in artificial saliva for 14 days.The morphology and phosphate radical changes of dentine surface were detected by Focused ion beam scanning electron microscopy(FIB SEM)and Attenuated total reflection fourier transform infrared spectrometer(ATR-FTIR).2.According to the random number table method,49 dentin samples were randomly divided into 7 groups(n=7):healthy dentin group,completely demineralized group,group A,group B,group C,group D and blank control group E.Except for the healthy dentin group,all other groups were treated with 0.5M EDTA for 14 days for compete demineralization,and then groups A,B,C and D were treated with Aominqing(?)for 1,4,7 and 14 days respectively,while group E was only placed in artificial saliva for 14 days.The surface morphology of dentin and the physicochemical properties of minerals were detected by FIB SEM,Energy dispersive X-ray(EDX),X-ray diffractometer(XRD)and ATR-FTIR.Results1.In partially demineralized dentin samples,FIB SEM showed that the longer the treatment time of Aominqing(?)was,the denser the formed deposits and the higher the degree of occlusion of dentin tubules were.At 14 days,the deposits were ordered and completely closed the dentine tubules.ATR-FTIR showed that the intensity of the absorption peak of phosphate increased gradually with the extension of the treatment time,and returned to the level of healthy dentin at 14 days.2.In completely demineralized dentin samples,FIB SEM showed that the longer the treatment time of Aominqing(?)was,the denser the formed minerals and the higher the degree of occlusion of dentin tubules were.EDX showed that the calcium-phosphorus content and the calcium-phosphorus ratio in group D were significantly higher than those in groups A,B and C and the difference was statistically significant(P<0.05).ATR-FTIR showed that the longer the treatment time of Aominqing(?)was,the higher the absorption peak intensity of phosphate was.XRD showed that groups B,C and D have formed diffraction peaks similar to hydroxyapatite.Conclusions1.It is a gradual process for the bioactive glass,Aominqing(?),to block the dentin tubules.According to the changes of surface morphology and phosphate racial in partially demineralized dentin samples,treatment with Aominqing(?)for 14 days can achieve a good effect.2.Aominqing(?)can form minerals on the surface of completely demineralized dentin similar to hydroxyapatite or hydroxycarbonate apatite structure,which promotes the remineralization of dentin and has a time accumulation effect.This change may be the underlying mechanism by which Aominqing(?)can block dentin tubules and exert a desensitizing effect.