The Effect Of Overdose Fluride On The Ultrastructure And Immunohistochemical Changes In Rat's Odontoblasts

Object : Dental fluorosis is a condition which increased fluoride exposure duringtooth formation results in a variety of pathological changes in structure andcomposition. Dental fluorosis spreads all over the world, it is wildspread andserious in our country. With extensive fluorized water and product containingfluoride used in recent years, fluorosed teeth become serious, fluorosed teeth hasbeen an important problem in the world. Previous studies have showed increasedfluoride exposure during tooth formation results in enamel and dentin changes.There were many reports concerning the influence of fluoride on enamel but few tothe dentin, and the mechanism of fluoride impact on odontoblasts is still unknown.At present, the reaearch in the effect of fluoride on the odontoblasts in cytology islittle. The present study is to observe the effect of overdose fluoride on theexpression of bFGF, TGF-β1 in rat odontoblasts. The present study is to discussmechanism of dental fluorosis in cytology, to further study the toxical mechanismof fluoride on odontoblasts , and to prefer a new methodology guidance, theoreticaland clinical evidences.Methods: 30 wister rats were divided into two groups: group I (control);group II20mg/kg/d Naf were given . After 8 weeks treatment, the change ofmorphology and ultrastructure of odontoblasts were observed by means of opticalmicroscope, transmission electron microscope, and immunohistochamicalstaining was adopted for studying expressions of bFGF, TGF-β1 in two groups ratincisors odontoblasts.Results:HE staining micrograph examination There was increasing interglobular dentinin the experimental group .The layers of Enamel and dentin were thinner thanthose in the control groups.Abrasive disk There were clearer incremental lines and cross striations in theexperimental group than the control group under optical microscope.Transmission electron microscope The odontoblasts ultrastructure of theexperimental group were changed: cell shrinkage, the number of cell apparatusdecreased. the nucleuo-cytoplasmic ratio increased, the number of nucleolusdecreased, the shape of nuclear were abnormal ,heterochromatin increased,euchromatin decreased, some cells displayed signs of apoptosis,as indicated bymembrane blebbing, chromatin condensation , nuclear fragmentation.Immunohistochamical staining The image analysis result showed that theexpression of bFGF and TGF-β1 in odontoblasts and inner dentin were inhibitedin group II as compared with the control group(p<0.01).Conclusion :1 The experimental model of rat dental fluorosis is developed after a high dose ofsodium fluoride treatment.2 In this research, part of odontoblasts cells begun apoptosis after cells receivedtoxic action, their energy and protein synthesis were affected;3 The overdose fluoride will inhibit the secretion of bFGF and TGF-β1, theninhabit the different and formation of the tooth –forming cells. which leads to theabnormal development of teeth.