An In Vitro Study Of The Remineralized Ability Of Sustained Release Fluorine Ion Poly (Propylene Carbonate) In Initial Enamel Caries

AIM:This study aims at testing the release amount of fluorine ion in sustained-release membranes of different molecular weight in different time periods,summarizing release characteristics and rules of fluorine ion.In the meantime,doing in vitro remineralization experiments,analyzing remineralization of sustained-release membranes of different molecular weight through observing the change of surface morphology and microhardness.METHODS:Experiment one:Dividing the sustained-release fluorine ion poly of 3 different molecular weights(50 thousand,100 thousand,160thousand)into 3 groups.After preparing the impregnated solution,testing and adding up the release amount of fluorine ion in 30 minutes,60minutes,24 hours and 168 hours(7 days).According to mono factor analysis of the data by statistical software,there was statistical significant when P<0.05.Experiment two:Randomly divide the early enamel caries,which were made of extracted teeth,into 5 groups,3 of which were the sustained-release membrane with different molecular weight,the blank control group was artificial saliva,and the positive control group was remineralized solution.The microhardness of enamel surface was measured before and after demineralization and remineralization.The different value of microhardness before and after remineralization was calculated and the data of all samples were processed by statistical software.Mono factor analysis of variance was used to analysis and LSD-t statistical test was used to compare the data among groups.There was statistical significance when P<0.05.Experiment three:SEM was used to observe the surface morphology of 5 groups of early enamel caries before and after demineralization and remineralization.RESULTS:Experiment one:The release amount of fluorine ion of the sustained release membrane of50 thousand,100 thousand and 160thousand was 52.50ug/ml,82.60ug/ml and 686.97ug/ml in 30 minutes.The release amount of fluorine ion of the sustained release membrane of molecular weight of 160 thousand was obviously higher than those in other groups and has statistical significance when P<0.05.The release amount of fluorine ion was 6.40 ug/ml,17.58ug/ml,46.23ug/ml in 60minutes respectively,63.01 ug/ml,92.36ug/ml and 154.57ug/ml in 24hours,and 244.61?g/ml?326.27?g/ml?47.69?g/ml in seven days.The release rate of fluorine slowed down in 60 minutes,24 hours and 7days.The cumulative release of fluorine ion of the molecular weight of 50thousand,100 thousand and 160 thousand on the 7~thh day was 366.52ug/ml,518.81ug/ml,and 935.46ug/ml respectively.The larger the molecular weight of the sustained-release membrane was,the greater the amount of fluorine release was.Experiment two:The results of microhardness measurement showed that there was no statistical difference in SMH value between 320and 340(P>0.05)before demineralization.After demineralization,the SMH values of each group were reduced compared with those before demineralization,and there was no statistical difference in 230~250(P>0.05).The SMH value in each group were increased and has statistical significance(P<0.05)after remineralization.The recovery percentage of SMH value of early enamel caries of the 3 groups of sustained release membranes with molecular weights of 50 thousand,100 thousand and160 thousand was 50.29%,79.64%and 84.83%respectively.In the blank control group,the recovery of saliva was 26.58%,while that of the positive control group was 52.81%.After the remineralization of the sustained release membranes of 50 thousand molecular,there was no significant difference between the SMH value and the remineralization solution(P>0.05).Experiment three:The results of scanning electron microscope showed that the surface of normal enamel was smooth before demineralization,crater after demineralization,and has mineral deposition on the enamel surface after remineralized,and there were more mineral deposits in large molecular weight sustained release membrane.CONCLUSION:The results of the measurement of release amount of fluorine ion in3 different molecular weight of sustained-release membranes showed that the rules of the release amount of fluorine ion was:the larger the molecular weight of the sustained-release membranes was,the faster the rate of releasing fluorine ion was,and the total release amount was the largest.The recovery percentage of SMH value of early enamel caries of the 3 groups of sustained release membranes was 50.29%,79.64%and84.83%respectively.The mineral deposition on the surface of the enamel was observed by scanning electron microscope,the larger the molecular weight of the sustained-release membrane was,the more the mineral deposition was,which was in accordance with the results of the microhardness value.In conclusion,polypropylene carbonate membrane as a carrier of fluoride ion is feasible.It can release fluorine ions and has the effect of remineralization.