The Study Of The Influence Of Different Selenium Concentration On The Development And Caries Susceptibility Of Rat Tooth In Vitro

Objective：To compare the impact of different levels of selenium on thedevelopment and caries susceptibility,we supplement developing ratswith different concentrations of selenium and establish cariogenic modelin vitro.It is expected to provide experimental reference for clinicalapplications.Methods:Experiment one:Study of the effects of different selenium concentrationson rat tooth development90-day-old female Wistar rats and90-day-old male Wistar rats weremated1:1.The conception of the12rats were randomly assigned toA,B,C,D four groups of three.Group A pregnant rats were fed with a dietof low selenium(Se0.015mg/kg),group B pregnant rats were fed with adiet of middle selenium(Se0.15mg/kg),group C pregnant rats were fedwith a diet of high selenium(Se1.5mg/kg),and group D pregnant ratswere fed with the basal diet(Se0mg/kg) as a control group.After naturalchildbirth of pregnant rats,pups which retained10in each group weregiven breastfeeding.Maternal diet in each group was the same as theformer.25-day-old pups were weaned,and their diet and drinking waterwere the same as the group of maternal’s respectively.The pups were sacrificed by cervical dislocation when they were44days old.Wedissected alveolar bone and got incisors and molars.The situation of thedevelopment of the teeth and jaws was observed by the naked eye,X-rayfilm and micro-hardness measurements.The results of micro-hardnessmeasurements were statistically analyzed.Experiment two:Study on the relationship between different seleniumconcentrations and caries susceptibility of rat tooth in vitroThe establishment of the cariogenic model and the dividing ofexperiment groups were the same as Experiment one.The four groups ofteeth and jaws were immersed in artificial cariogenic fluid and taken out aweek later.Diagnosis and keep a record of demineralized situation ofthe third molars in each group by Enhanced visual methods andDIAGNOdent.10pups teeth of each group were selected randomly,andgradient polished to100μm~150μm thick samples with diamondpolishing papers.Then the samples were immersed in Rhodamine B for1hour.Fluorescence excitation conditions of dental tissue was observed byconfocal laser scanning microscopy.Average Fluorescence and depth ofdemineralization were analyzed through computer.The data of threemethods was analyzed using SPSS16.0statistical software.Results:①Macroscopic observation: Maxillary incisors of group A wereyellow-brown.Their transparency and glossiness were the best,followedby group D.Group B was yellow, which glossiness was poor, and part oftooth surface appeared white opaque regions.Group C was the worst. X-ray photography showed:Mandibular molars of group C had thehighest transmittance,the thinnest root canal wall and the largest pulpcavity.This phenomenon was mitigated with the decrease of seleniumconcentration.Micro-hardness tests results:There was significantdifference in microhardness of four groups(p<0.01).Hardness values ofgroup A was the highest which were significantly different from the othergroups(p<0.01). Hardness values of group C was the lowest.Group D wasslightly higher than group B,but there was no significant differencebetween them(p>0.05).②Enhanced visual methods results:The demineralization of group Cwas the most serious and significantly different comparing with otherthree groups(p<0.01).Demineralization degree of Group B was slightlyhigher than that of group D,but there was no significant differencebetween the two(p>0.05).Demineralization of group A was the least,andthere were statistically significant differences between the fourgroups(p<0.01).DIAGNOdent showed:The demineralization of molarocclusal surface of four groups was significant difference(p<0.01).GroupC was higher than the other three groups(p<0.05),and followed by groupB.Both of their DD values were higher than that of group D,whiledemineralization of group A was at the minimum level. And thedifference was statistically significant between group A and groupD(p<0.05). CLSM indicated: The AF of four groups was significantlydifferent(p<0.05). Group A was minimum, while group C wasmaximum.Group B was higher than group D.There was significant difference between A and C(p<0.01).But there was no statisticallysignificant among the rest groups(p>0.05). Demineralization depth offour groups was different significantly(p<0.01). Group A which wassignificantly different with group B and C was a little lower than groupD.Demineralization depth of group C was the deepest,but no significantdifference with group B and D(p>0.05).Conclusions:①Selenium is involved in the process of tooth development,andthe influence on tooth development has a clear relationship to itsconcentration.Low levels of selenium promotes the development of toothwhile high levels of selenium is contrary.②Many factors impact on caries susceptibility of the host.Development and mineralization of tooth have a great effect on cariessusceptibility.③The relevance of selenium and caries susceptibility is obvious.The supplement of different selenium concentrations makes cariessusceptibility different. High levels of selenium increase cariessusceptibility,while low levels of selenium is contrary.