| Objectives: The models of incipient enamel demineralization afterorthodontic treatments were established in an artificial method. Through theenamel surface color changes and surface morphology changes, the effects ofinfiltrating resin and fluorinated foam on incipient enamel demineralizationafter orthodontic treatments were compared, which would provide referencesfor the clinical applications of the two methods.Methods:75freshly extracted human premolars of patients fororthodontic reasons from Hospital of Stomatology, Hebei Medical University,were collected for the experiment. The cervical third of the labial surface ofthe teeth after cleaned and disinfected, was as a window area, while the rest ofthe enamel was covered with two layers anti-acid nail oil. To establishincipient enamel demineralization models, the teeth will be soaked into thepartial saturated acid buffer with37℃constant water bath for two weeks.75teeth were then randomly divided into three groups: Group A-control:deionized water. Group B-fluorinated foam: fluorinated foam. Group C-resininfiltration: infiltrating resin. All teeth were stored in artificial saliva for8weeks with37℃constant water bath, changed every24hours. Theassessment of colour was performed by the Olympus Crystaleyespectrophotometer in four distinct stages: before demineralization, afterdemineralization (t0), immediately after different treatment (t1), after4weeks(t2), after8weeks (t3). All images were analysed by images processingsoftware (Crystaleye Application Ver1.4) for the average values of L of thecervical third of the labial surfaces. From t1to t3stage,△L was calculatedseparately with t0stage, which were recorded as△L1,△L2and△L3. Themeasurement of surface morphology was performed by Scanning Electron Microscope (SEM) in the following distinct stages: after demineralization andafter4weeks. All data was analysed by the statistical software SPSS13.0:1.The Repeated Measures ANOVA was carried out to analyse△L1,△L2and△L3of Group A, B and C.2. The Student-Newman-Keuls test was used tocompare the means of△L of Group A, B and C.Results:1The naked eye viewAfter demineralization, the teeth enamel surfaces of Group A, B and Cturned into chalk color and became rough. The enamel surfaces of Group Ahad no obvious change immediately after treated by deionized water, withtime going on, the changes of color and roughness of enamel surfaces were notobvious. The enamel surfaces of Group B had no obvious changesimmediately after treated by fluorinated foam, over the time, the chalk color ofenamel surfaces decreased, the surface roughness reduced, and the teethrestored some glossiness. The chalk color and the roughness of enamelsurfaces of Group C disappeared, immediately after treated by infiltratingresin, almostly returning to the normal enamel appearance, with time going on,enamel appearances had no obvious change.2The changes of the value of L2.1The comparison of the value of L of three groups (A, B and C) after theproductions of the demineralization models (t0): the values of L of threegroups satisfied normal distribution and equal variance, the single factoranalysis of variance (ANOVA) P=0.672>0.05, indicating that there were nosignificantly statistical differences among Group A, B and C, the baselines ofthe three groups before treatments were consensus.2.2Repeated measurement ANOVA of the three groups (A, B and C): therewere significantly statistical differences in groups (treatment factors)(P <0.05), indicating that the treatments of Group A, B and C had effects on thevalues of△L; there were significantly statistical differences in time (P <0.05), indicating that there were differences in△L at different times; therewas interaction between time factors and group factors (treatment factors)(P < 0.05).2.3The comparison of the means of△L among the three groups(A, B andC): Group A-1.334±0.340, Group B-3.561±0.340, Group C-13.043±0.340,according to the inspection standard α=0.05, Student-Newman-Keuls testrevealed that there were significantly statistical differences among threegroups (P <0.05), the means of△L of Group C (Resin infiltration) was themaximum, followed by Group B (fluorinated foam), and Group A (Control)was the minimum.2.4The curve of the changes of△L with time: The average value of L beforedemineralization was taken as the baseline,△L was calculated at every timestage with the baseline. At the t0stage,△L of the three groups all reached10-12. Immediately after treatment (t1),△L of Group C returned to0nearby,indicating the value of L was close to normal enamel, but Group A and GroupB had no obvious changes. For8weeks,△L of Group C had still stayedaround0without obvious changes, but△L of Group A and Group B haddecreased gradually. The change at t3was slower than that at t2, and thevalues of L of Group A and Group B, which were around8, were higher thanthat before demineralization.3The results of enamel surfaces by Scanning Electronic Microscope (500times):The enamel surfaces after demineralization were rough and uneven, withhollows in different sizes.4weeks after different treatments, surfaces ofGroup A and Group B were still rough and uneven, and some of the hollows,due to the remineralization, became shallow and even disappeared. There weremineral particles and flakes of minerals deposit on the enamel surfaces, Someof the hollows still remained. But the enamel surfaces of Group C weresmooth, flat and homogeneous, with no obvious hollows.Conclusions:1Infiltrating resin can be used for incipient enamel demineralizationafter orthodontic treatments. It can improve appearances of teeth at a timewithout teeth damage, which is stable in a short term. 2Fluorinated foam can promote incipient enamel demineralization afterorthodontic treatments to remineralization, but it’s slow and the changes ofappearances of teeth were not obvious. |
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