| Objective: To evaluate and compare the effects of tooth mousse, fluorideand their combination on inhibiting enamel demineralization and their effectson the shear bond strength of orthodontic brackets bonded to enamel surface,and provide experimental evidence for the clinical use.Methods:98freshly extracted human first premolar teeth were collectedin orthodontic treatment for the experiment. Chose48of them for the first partof the experiment, made3mm×3mm blank areas at gingival side of the labialsurface for these48crowns with acid-fast nail polish, measured the Vickersmicrohardness of the blank areas of the enamel surfaces, Then these sampleswere randomly divided into4groups according to their microhardness values,with12teeth in each group, the blank areas of the four groups were treatedwith the following method, Group A was considered as the control of othergroups, with no treatment, group B were applied with Fluoride varnish, with afrequency of once15days, and5minutes every time, tooth mousse werecoated on the surface of teeth for group C, with a frequency of once every day,and30minutes every time, group D were first applied with Fluoride varnish,5minutes every time, once15days, and then applied with tooth mousse, onceevery day,30minutes every time. All the4groups were immersed in PH4and PH6.8artificial saliva by turns, after the treatment of sixteenth days, themicrohardness of all the samples were measured once again, observed themorphological changes of enamel surface. The remaining40first premolarswere randomly divided into four group, with10teeth in each group, the buccalcentral part of the4groups were treated with the following method: group Awas considered as a control group, with no treatment, group B were appliedwith Fluoride varnish for5minutes, Group C were coated in tooth mousse for30minutes, group D were first applied with Fluoride varnish for5minutes and then with tooth mousse for30minutes, cleaned all samples, orthodonticbrackets were bonded to the clinical center of all specimens as common clinic,after immersed in artificial saliva for48hours, the specimens were tested forthe shear bond strength of orthodontic brackets. The microhardness value wereanalysised with One-way ANOVA, The analysis of variance was used tocompare the shear bond strength for the four groups.Results:1The morphology of enamel surface was observed on the sixteenth day ofexperiment, the enamel surfaces of group A were white and gloomy, there wasno obvious color change in group D, some of the enamel surfaces of group Band group C were seen white and gloomy, there was not obvious color changebefore the treatment.2The result of One-way ANOVA analysis indicated that, according to ɑ=0.05level, statistically significant difference was found among the microhardnessvalues of four groups(F=16.28,P<0.05). The analysis of LSD-t tests showedthat, according to ɑ=0.05level, statistically significant differences were foundbetween any two groups except group B and group C.3The result of One-way ANOVA analysis showed that there was significantdifference among the shear bond strength of orthodontic brackets of fourgroups(F=23.05,P<0.05). The analysis of LSD-t tests showed that, there wasno statistical significance between any two groups except group A and groupC, group B and group D, The shear bond strength of each group ranked fromstrong to weak as blow: A> C> B> D.Conclusion:1Fluoride varnish, tooth mousse, and their combination can effectivelyprevent tooth surface turning white.2In this experiment, the Fluoride varnish, tooth mousse and their combinationcan inhibit enamel demineralization, the effect of the combination applicationof Fluoride varnish and tooth mousse was better than the two separateapplication, the effect of the tooth mousse was the same as fluoride varnish, the effect of artificial saliva in promoting demineralized tissue remineralizewas poor.3The combination application of Fluoride varnish and tooth mousse beforeacid etching will reduce the shear bond strength of bracket, so does Fluoridevarnish alone, they cannot be used to prevent tooth demineralization in cliniclike this way; The application of tooth mousse before acid etching did notinfluence the shear bond strength of bracket, it can be used in clinic inpreventing tooth demineralization. |
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