| As an active tooth-bleaching ingredient,hydrogen peroxide has been applied in clinical,which has effective to change discolored teeth and also obtained the good clinical therapeutic effect.Hydrogen peroxide,as a powerful oxidant,has a series of effects on organic and inorganic compounds of the teeth.Raman spectroscopy,as a kind of effective,non-destructive,non-invasive analysis techniques,which can be detected the component changing during the bleaching treatment at the molecular level.Nevertheless,for the biological tissues,there was a very strong fluorescence background of the Raman spectrum.Exposing to bleaching treatment,the Raman fluorescence background significantly decreased after hydrogen peroxide treated,at the same time,the color of the teeth had also been obviously changed.For the two parameters,there was a strong correlation between them.For the mechanism of the bleaching,there was no consistent conclusion about the mechanism of hydrogen peroxide bleaching teeth.This thesis through the background of Raman spectrosocopy laser-induced fluorescence intensity changing,in order to explore the materials that generates Raman laser induced fluorescence to explain the mechanism of bleaching treatment in a new view point.For the first experiment,exposing to the prolonged time hydrogen peroxide treatment,the tooth color,Raman fluorescence intensity of the human dentin samples Raman spectrum had a different changing tendency with the organic matrix of the human dentin.It was concluded that collagen proteins,as the major organic matrix of the human dentin,did not induced the Raman fluorescence of the human dentin;it might be only a minority of the total organic matrix of the human dentin component.In the second experiment,the different chemical agent were used to deal with the non-collagen proteins of the human dentin,the results confirmed that the existence of the non-collagen proteins of the human dentine had a strong relationship with the Raman fluorescence.The Histochemical staining of the treated human dentin sections also verify the results.At the same time,using the mass spectroscopy analyzed the extracted non-collagen proteins of the human dentin.It was showed that serum albumin has the very high suitable with the results of the mass spectroscopy.In order to verify the result of second experiment,hydroxyapatite,under different concentration condition of bovine serum albumin,was synthesis at the room temperature in vitro.The results of the experiment indicated that the Raman fluorescence intensity of the synthesized hydroxyapatite significantly increased with the bovine serum albumin incorporated in the hydroxyapatite.It was also observed that the fluorescence intensity of the hydroxyapatite increase with the increase of content of bovine serum albumin.Experiment ? Effects of prolonged neutral hydrogen peroxide treatment on Raman fluorescence of human dentinObjective:to explore the changing tendency of the Raman fluorescence of the human dentin under prolonged time treated by neutral hydrogen peroxide.Materials and Methods:Human dentin specimens were randomly divided into two groups treated with either neutral 30%hydrogen peroxide solution(HP)or distilled water(DW),respectively.Attenuated total reflection infrared spectroscopy(ATR-IR)and Raman spectroscopy were used to monitor the chemical component and the Raman fluorescence changing under the prolonged HP treatment.The changing tendency of the tooth color was measured by spectrophotometer at the following time points:0 day,1 day,3 day,7 day,14 day and 28 day.At the same time points,the morphology and fracture toughness of the dentin samples were measured by scanning electron microscopy(SEM)and fracture toughness test.Results:In the control group,the color,relative Raman intensity(RRI)and Raman fluorescence intensity(FI)of the human dentin were not change significantly after treatment.Mineral:Matrix ratio and amide I peak intensity of the infrared spectroscopy were only slightly change after the treatment.For the neutral HP group,the RRI of the dentin samples did not change significantly,while the FI,tooth color,the Mineral:Matrix ratio and amide I peak intensity of the infrared spectroscopy were changed significantly after 24 hours treatment.However,the RRI and the color of dentin samples did not continue to change with prolonged time treatment.Mineral:Matrix ratio and amide I peak intensity continued to change with the increase of treatment time.The results of fracture toughness of neutral hydrogen peroxide groups decreased with the treatment time,and the fracture surface morphology of human dentin was change obviously over time.Conclusions:The change tendencies of the dentin color and Raman fluorescence intensity under prolonged hydrogen peroxide treatment are not directly related to the inorganic components of human dentin,and the substances that cause color and Raman fluorescence change are might be only partially of the organic components of the dentin constituents.Experiment II The changing tendency of laser-induced Fluorescence of human dentin under the different treatments and preliminary exploring the origin of laser-induced fluorescenceObjective:To study the changing tendency of dentin Raman fluorescence under different treatments and preliminary explore the substances that cause dentin Raman fluorescence changes.Methods and methods:Dentin samples were randomly divided into four groups:deionized water(DW)group,neutral hydrogen peroxide(HP)group,ethylenediamine tetraacetic acid disodium salt(EDTA)group and acetic acid(AA)group(n = 10)according to different treatment methods.Raman spectroscopy and infrared spectroscopy were used to measure the Raman fluorescence intensity and the organic component of the human dentin before and after treatments.Morphologies of dentin samples in different groups after the treatments were observed by field emission scanning electron microscopy.Weight Changes of dentin samples after different treatments were measured by thermo gravimetric analysis.The non-collagenous proteins were extracted and then separated the component by sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS-PAGE).In addition,the longitudinal teeth sections were treated by different treatment methods and then all the treated sections was stained by Stains all.After staining,the sections were observed by optical microscope.Results:After different treatments,the changing tendencies of the relative Raman intensity(RRI)and Raman fluorescence intensity(FI)of human dentin were different among the different group.For the control group,both the RRI and FI were no significant change after treatment.For the EDTA group and AA group,the RRI of the dentin samples significantly decreased after treatments,but the FI had different changing tendency.For the EDTA treatment group,the FI decreased significantly after treatment,while in the AA group,the FI had only slightly change after treatment.For the results of the infrared spectroscopy,the change trend of Mineral:Matrix(M:M)ratio was different after different treatments.For the control group,the M:M ratio only slightly changed after the treatment.However,for the HP group,M:M ratio was obviously increased.For the AA group and EDTA group,M:M ratio decreased significantly compared with the results of control group.For the different groups,the percentage of weight loss was different after the treatments between 200? to 600?.The percentage of weight loss was no statistically significant different between the control group and HP group.The results of polyacrylamide gel electrophoresis of the non-collagen proteins that extracted from dentin samples under different treatments showed that there was an obvious difference between HP group and DW group and AA group.After different treatments,the longitudinal tooth sections were stained by Stains all.The dentin part of the sections of the control group and the AA group were stained blue-violet,while the dentin part of the tooth sections of the EDTA group and the HP group did not stain.Conclusion:The FI changing tendencies were different after the different treatments.The substance that causes the dentin sample Raman fluorescence is closely relate with the non-collagenous proteins(NCP)of the human dentin.Experiment ? Changes of Raman Fluorescence of hydroxyapatite Synthesized with Different Concentration of Bovine Serum AlbuminObjective:To observe the changing tendency of Raman fluorescence intensity of the hydroxyapatite synthesized under different concentrations of bovine serum albumin.Materials and methods:Calcium nitrate solution with different concentrations serum albumin was prepared and reacted with diammonium phosphate solution to synthesize hydroxyapatite.The Raman spectroscopy used to measure the Raman spectra of the hydroxyapatite that synthesized under different conditions.Results:Hydroxyapatite synthesized under different conditions had different Raman fluorescence intensity.With the increase of bovine serum albumin concentration,the Raman fluorescence intensity of hydroxyapatite also increased.Conclusion:Bovine serum albumin affects the Raman fluorescence intensity of the synthesized hydroxyapatite,and its intensity changes in a concentration-dependent manner,increasing as the amount of bound serum albumin increases. |
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