The Study Of The Remineralization Effect Of Different Concentration Of Silicon On Demineralized Enamel In Vitro

Objective:To provide experimental evidence for clinical prevention of earlycaries, three trials were done. In this study, the models of artificialdemineralized enamel were prepared in vitro. The effect of differentconcentration of silicon on demineralized enamel was observed andevaluated by SEM and microhardness tester. And the ratios of calciumand phosphorus on the surface of enamels which were treated byremineralization solutions were analysed via EDS.Methods:Experiment one: The observation of enamel surface morphology ofremineralization samples which were treated with different concentrationof siliconAccording to the requires that the extracted teeth’s enamel surfacesneeded to have no white, no caries, no defects, no cracks, we collectedthirty premolars or molars which were removed because of orthodonticand periodontal disease. We cut the30extracted teeth’s roots with the thehigh speed handset and then retained the crown. And then we separatedthe buccal and lingual with low speed sectioner and retained the buccalparts. Each sample was painted with two Iayer of nail varnish leaving a4mm*5mm window on the buccal parts. We divided them into fivegroups randomly, they were defined as group A1, group B1, group C1,group D1, group E1, which contained0ppm, o.5ppm,1.0ppm,8.0ppm, 16.0ppm respectively. And group A1was the control group, the otherswere the experimental groups. Each group contained six enamelspecimens. The specimens were placed in the lactic acid gel (thewindowing area was upturned) and taken out a week later. Then the fivegroups of demineralized model were placed in five groups ofremineralization solutions respectively for three weeks. Finally, theenamel surface morphologies of the demineralization samples and theremineralization samples were observed by SEM.Experiment two: The hardness measurement of remineralization samples＇enamel surfaces which were treated with different concentration ofsilicon.The preliminary preparation and grouping of specimens was thesame with the experiment one. The groups were group A2, group B2,group C2, group D2and group E2, respectively (A2was the control group).Each group contained five enamel specimens. The windowing areas werepolished to be flat and level with diamond polishing papers. Then thespecimens were placed in the lactic acid gel (the windowing area wasupturned) and taken out48hours later. The five groups of demineralizedenamels were placed in five groups of remineralization solutionsrespectively. Then the specimens’ surface hardness were measured beforethe experiment, at the time of48hours after demineralization and at thethird week of remineralization. The results of microhardnessmeasurements of five groups’ specimens were analyzed using SPSS19.0statistical software.Experiment three: The analysis of the ratio of calcium and phosphorus onthe enamel surface which were treated with remineralization solutionscontaining silicon.The preparation of specimens was the same with the experiment one.We divided the specimens into two groups randomly, they were group A3 and group B3.Each group contained five enamel specimens. Then thespecimens were placed in the lactic acid gel(the windowing area wasupturned)and taken out48hours later. Then group A3was treated with thebasic remineralization solutions, and group B3was treated with theremineralization solutions whose effect on remineralization was the bestwhich found in experiment one and two。After three weeks, the specimensof group A3and B3were taken out from remineralization solutions. Weanalyzed the elements on the enamel surface of each group by EDS afterdried and then calculated the ratio of calcium and phosphorus. The ratiosof calcium and phosphorus which we calculated were analyzed usingSPSS19.0statistical software.Results:①The results of SEM: we could observe that a chalky color andmatte finish on the windowing area of five groups of specimens afterdemineralization with the naked eyes. The observation of SEM showedthat the enamel surface of specimens appeared pits, and the center ofenamel prisms was dissolved. Interprismatic substance was relativelyintact. The morphology of enamel surface was honey comb type. Therewas no significant difference in the morphology of enamel surface amongthree groups.The chalky changes on enamel surface had been reduced and mostof the enamel surface’s luster had been restored after the treatments withremineralization solutions which contained no silicon or containeddifferent concentration of silicon. We could see different appearance byscanning electron microscopy. Compared with the control group, all thesolutions had remineralization effect, especially group D1. Theremineralization effect on demineralized enamel increased with theincreasing of silicon concentration in group B1-D1. When theconcentration of silicon increased to group E1, the remineralization effect of silicon decreased compared to group D1.②The results of MH measurement：The hardness values of eachgroup had increased after remineralization, but did not reach the hardnessvalue of enamels which were not treated with anything. The largestincrease of the hardness values was group D2, followed by group C2, E2,B2, A2. There was significant difference between group A2and othergroups (P<0.01). There was significant difference between group D2andother groups (P<0.05). The hardness values of group C2was higher thangroup B2and group E2, but there was no significant difference amongthem. The hardness values of group E2was higher than group B2, butthere was no significant difference between them.③The results of EDS measurement: the enamel surface of group A3contained oxygen, calcium, phosphorus and other elements except silicon.The ratio of calcium and phosphorus was Ca/P=1.98±0.57. In addition tooxygen, calcium, phosphorus and other elements, the enamel surface ofgroup B3contained silicon. The ratio of calcium and phosphorus wasCa/P=2.28±0.17, which was significantly higher than group B3, and therewas significant difference between them (P<0.05).Conclusions:①Silicon had an effect on promoting remineralization ofdemineralized enamel.②The remineralization effect of different concentration of siliconwas different. The remineralization effect was the best when theconcentration of silicon was8.0ppm. When the concentration of siliconwas at0~8.0ppm, the remineralization effect of demineralized enamelincreased with the increasing of silicon concentration. When the concentration of silicon was over8.0ppm, the remineralization effect ofsilicon decreased.③The reasons of silicon promoting remineralization might be thatsilicon may be able to promote the deposition of calcium and phosphorus.And it presented as a complexes of silicon calcium phosphate.