| Objectives Preparation the model of early cementum caries on first mandibular premolars,different drugs and methods were used to compared the remineralization efficacies in the early cementum caries.Evaluation criteria include the topography,roughness,microhardness,calcium phosphorus mass ratio and fluorescent dye area of the cementum surface.This in vitro study aims to explore the different remineralization efficacies for the early cementum caries between 6% bioactive glass(BAG);casein peptide phosphate-the amorphous calcium phosphate paste(CPP-ACP);2% sodium fluoride(2%Na F)solution and single use diode laser irradiation combined with 6% BAG.Methods 1 Experiment I: There are 96 pieces of cementum prepared.Random allocation was taken for them to divided into four groups: 6%BAG(Group A,n=24),CPP-ACP(Group B,n=24),2%Na F(Group C,n=24),deionized water(Group D,n=24).Before demineralization,use the electron microscope to observe the initial human cementum morphology which is taken from each group.Fluorescence staining was performed to observe the fluorescence effect before the establishment of early cementum caries,take samples from four group.5 pieces were randomly selected from the remaining 22 pieces of each group to detected the cementum surface topography with atomic force microscope(AFM)and the hardness with vickers surface microhardness tester(SMH)before demineralization,and then put them back into the original experimental container.All the left cementum slices were putted in 37? artificial demineralization of liquid for 96 hours so as to preparation early root caries model for later.Then 1 piece of sample was selected from each group for electron microscopy scanning to observe the surface morphology of cementum before re-mineralization.Another 4 samples from each group were selected to observe the fluorescence effect before remineralization.Five pieces of each group were selected from the remaining cementum to be used for AFM and microhardness tester testing before remineralization,and then put them back into the originnal container.p H cycles of five minutes three times a day for a total of 20 days were performed on the samples,and then the samples were tested by AFM,SMH,scanning electron microscope(SEM),energy dispersive spectrometer(EDS)and inverted fluorescence microscope(IFM).Experiment 2:96 cementum samples were prepared,then randomly divided into four groups: 6% BAG + diode laser(Group E,n=24),6%BAG(Group F,n=24),diode laser(Group G,n=24)and deionized water(Group H,n=24).The process is the same as experiment 1.After the early root caries models were prepared.Group E: the 6% BAG was repeatedly and uniformly coated on the cementum surface for 5 minutes,subsequently,2 minutes of laser "Z" type mobile irradiation,and then the samples were rinsed with deionized water.Group F,6%BAG was repeatedly and uniformly coated on the cementum surface for 5 minutes,and then rinsed with deionized water.Group G :coated with deionized water for 5 minutes,followed by 2 minutes of laser "Z" type mobile irradiation,and then the samples were rinsed with deionized water.Group H :deionized water coated for 5 minutes.Finally samples were tested by AFM,SEM,EDS,and IFM.Results Experiment 1: 1 AFM test showed that the cementum surface of group A and C was relatively smooth,and there was no statistical difference in roughness between the two groups(P>0.05),while there was a statistical difference between the all left other groups(P<0.05).2 The vickers microhardness test showed that the difference value of microhardness was the highest in Group A after mineralization(P<0.05),followed by the significant difference between Group B and C(P<0.05).3 Scanning electron microscopy showed that the surface of cementum before demineralization was smooth and present as fish scales.The cored collagen fibers and dentin tubules were exposed before remineralization.After remineralization,the surface of Group A was smooth with gravel-like crystal deposition.In the Group B,honeycomb hollowed out structures on the surface of samples were reduced,and there was sand and gravel material accumulation,and some dentin tubules were exposed.In Group C,the root surface was relatively smooth,and part of dentin tubules have particle accumulation.In Group D,the cementum surface formed tiny pits and scaffolded structural voids,and a large number of dentin tubules and collagen fibers were exposed.4 X-ray energy spectrum analysis showed that the calcium and phosphorus ratio of Group A was similar to that of the pre-demineralization cementum,there was no statistical difference(P>0.05).Group C has the highest calcium phosphorus ratio,which was the lowest in Group D.5 Fluorescence microscope test showed that pairwise comparisons were statistically significant(P>0.05).The fluorescence bands of Group A were the shallowest and the total fluorescence area and the total fluorescence intensity were the weakest.Experiment 2: 1 AFM showed that Group E and G were more rough then other groups,but there was no statistical difference between the two groups(P>0.05),and there was a statistical difference between the two groups and other groups(P<0.05).2 Vickers microhardness instrument showed that after remineralization Group E had the highest SMH difference(P<0.05),followed by Group E,which was statistically different from the Group H(P<0.05).3 SEM showed that Group E had a large number of fused crystals covering the surface of cementum,and a large number of gravel-like crystals were deposited.The honeycomb hollowed out structure on the surface of Group F was reduced,and there was gravel like material deposition.No collagen fibers were observed in the Group G.4 X-ray energy spectrum analysis showed that the calcium and phosphorus ratio of Group E was similar to that of pre-demineralization cementum,with statistical difference(P<0.05),followed by the significant difference between Group F?G and H(P<0.05).5 IFM test showed that pairwise comparisons were statistically significant(P>0.05),The fluorescence bands of Group E were the shallowest and the total fluorescence area and the total fluorescence intensity were the weakest.Conclusions 1 BAG can promote the remineralization of early root caries.2 Single coating of BAG combined with semiconductor laser can promote the remineralization of early root caries.Figure: 18;Table 8;References 242... |
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