Experimental Study On The Development Of Enamel To Tooth Germ Trauma And Fluorosis In Rats

ObjectiveTo establish a rat model of abnormal development of enamel caused by tooth germ trauma and dental fluorosis,to understand the enamel structure and contents of calcium and phosphorus in the enamel by scanning electron microscopy and energy dispersive spectroscopy,;to observe the enamel structure change after acid etching;to compare the effect and microstructure changes after bleaching treatment.So as to provide a theoretical basis for the abnormal development of enamel in different clinical treatment.Method30 SD rats of 1 day aged were randomly divided into three groups,10 rats in each group.The control group(A group)without any treatment.The tooth germ trauma group(B group),At the rat mandibular incisors,gave it a vertical compression of a force of 10 N per 5mm2,to establish a dental trauma rat animal model.The dental fluorosis group(C group),when the rats 3 weeks old,50mg/l fluoride water preparation,daily free diet,to establish an experimental animal model.After 1 month of the experimental intervention,when the animal models had established,the rats were killed,and stripped the rat incisors.Then each group of experimental teeth(18 teeth in each group)were randomly divided into 3 groups.Each group have 6 teeth,blank group(labeled A0,B0,CO),bleaching treatment group(labeled A1,B1,C1),acid etching group(labeled A2,B2,C2).Scanning electron microscope and energy spectrum analysis were used to compare the changes of the experimental teeth and the surface structure and the contents of Ca and P in each group.Result1.Tooth germ trauma and high concentration of fluoride can cause abnormal development of enamel.2.Gross observation,teeth in group A were normal adorable,all the enamel were developed normal.In the B group,the tooth ectopic eruption were 4 cases,single anterior tooth eruption were 2 cases,and 6 cases have chalk spots.In C group,appear white spot at enamel surface were 4 cases,6 cases of brown and white stripes,4 cases of enamel defects.3.Enamel compared: normal enamel surface smooth,had pale yellow and uniform color.The injured teeth had a white enamel surface or enamel defects with clear boundary,in the absence of white spot enamel,transparency increased,showed white..Dental fluorosis have enamel opaque spot area,with yellow and white stripes,yellow teeth dye,enamel defects.After acid etching,enamel surface in three groups were turned into white and opaque yellow dye removal.And three had not obvious change after bleaching.4.SEM showed that the surface of untreated,normal tooth group A0 teeth had a smooth enamel surface layer of enamel structure without covering,no enamel defects.Traumatic teeth in group B0,the whole tooth surface is smooth,more cracks.in the white spots visibled enamel surface uneven,appearance of enamel demineralization area.C0 group of enamel fluorosis,the smooth surface without white spot area had no difference with normal occlusion,white spot area of enamel surface showed roughness,there is glaze column structure and large cracks in the enamel defect area can be exposed and visibled deep dentin enamel structure local defect area.After bleachingt: changes in the surface of A1 group were not obvious,only at high magnification,the surface became rough,some small enamel uneven surface mineralization.B1 group adversed demineralization.in group C1,the demineralization is not obvious,or only scaly demineralization.After acid etching,The A2 group can clearly see the enamel glaze column arranged orderly,clear structure,clear glaze and glaze column space.the group B2 enamel structure and glaze clearance visible,clear boundaries,but the enamel column spacing widened,arranged in neat.C2 group showed normal teeth without enamel rod part were missing,the crystal structure were loose and column were arranged tightly.5.Energy spectrum analysis showed that the untreated enamel surface in traumatic tooth enamel dysplasia,Ca,P content is low(P<0.05).After bleaching.B1,C1 compared with the A1,Ca,P content were significantly increased(P<0.05),but there was no significant difference between B1 and C1.Normal occlusion in after acid etching,A2,B2,C2,Ca between the three groups,the content of P was not statistically significant(P>0.05).ConclusionsThere are some differences at enamel hypoplasia of enamel surface structure between tooth germ trauma and dental fluorosis,and the sensibility was different to cold-light whitening.In the clinical work,we should have the different method for the enamel hypoplasia.