| Objective:To study the safety of fluoride-removing material on teeth and dynamically observe teeth remineralization in vivo after decoloring treatment on fluorosis mice tooth from fluorosis model.Methods:(1) 65 3-week-old Kunming mice were randomly divided into 2 experimental groups (n=30) and a control group (n=5).The mice in two experimental groups was fed with distilled water containing 100mg/ L(high-fluoride group) and 50mg/L(low-fluoride group) of sodium fluoride respectively. The mice in control group was given normal diet.42 days later, all mice incisors change were observed about transparent, luster, shape and the enamel microstructure was observed by scanning electron microscopy (SEM). (2) The high-fluoride group was randomly and equally divided into 5 experimental groups and 1 control group. The mice incisors in 5 experimental groups were treated by different methods:A group treated by Beyond fluoride-removing material I solution, B group by Beyond fluoride-removing material I solution after beening used Beyond cold-light technique, C group by Opalustre micro abrasion, D group by polishing cup, all mice above immediately killed after treatment, E group by Beyond fluoride-removing material I solution and killed two weeks later. The control group was given no treatment. All mice were taken four incisors which were made into specimens respectively for electron microscopy scanning (SEM), energy dispersive X-ray spectroscopy (EDS), micro-hardness test and histological examination. (3) The low-fluoride group was also randomly and equally divided into 5 experimental groups and 1 control group. The mice incisors in 5 experimental groups were treated by different methods:A group treated by Beyond fluoride-removing materialⅠandⅡsolution, B group by Beyond fluoride-removing materialⅠandⅡsolution after beening used Beyond cold-light technique, C group by Opalustre micro abrasion and remineralizing solution, all mice above immediately killed after treatment, D and E group were treated as A group and respectively killed 1 week and 2 weeks later. The control group was given no treatment. All mice were taken four incisors which were made into specimens respectively for electron microscopy scanning (SEM), energy dispersive X-ray spectroscopy (EDS), micro-hardness test. All data were analyzed by software spss 10.0.Results:(1) 42 days later, all chosen incisors of mice were examined. In high-fluoride group, the incisors enamel experienced changes in different degrees, such as scattered white spots, surface defects and even cut worn and pulp exposed; SEM observation showed the uneven enamel surface, cord-like structure arranged in irregular in enamel defects. In low-fluoride group, the incisors enamel surface showed transparent band or chalky patches; the SEM observation showed that the enamel surface was smooth and no defect. After enamel etching, some enamel rods slightly disordered and slightly irregular in size and shape, but most arranged as a certain direction. In control group, all incisors surface showed translucent enamel brown, smooth and shiny, the SEM observation showed that the enamel surface was smooth and dense, enamel rods were arranged in neat rows, size and shape was almost exactly the same and arranged according to a certain direction after enamel etching. (2) SEM observation showed that the enamel of A,B groups was severely demineralized and rough; C group was lightly demineralized than A,B group; E groups was mineral deposition uniformity and the enamel surface was smooth. There was significantly difference on the data about Calcium, phosphorus and calcium/phosphorus ratio among A,B,C,D,E,control group(P<0.05); whereas, there were no difference among A,B,C groups and no difference among D,E,control group (P >0.05). There was significantly difference on micro-hardness among A,B,C,D,E,control group(P<0.05); whereas, there was no difference among A,B,C groups and no difference among D,E,control group (P>0.05) A,B,C groups showed that pulp hypermia, further more B group was associated with tissue edema; whereas, D,E,control group showed normal pulp tissue. (3) SEM observation showed that there was mineral deposits on teeth surface in all 5 groups, which was more and even in A,C group than in the B group, more uniform mineral deposits in D group than in A group, more mineral deposits,more uniform and more smooth in E group than in D group. There was no significantly difference on the data about Calcium, phosphorus and calcium/phosphorus ratio among A,B,C,D,E,control group(P>0.05). And there was no significantly difference on micro-hardness among A,B,C,D,E,control group(P>0.05).Conclusions:(1) The model of a typical dental fluorosis can be established by making mice drinking high concentrations of fluoride water.(2) Fluorosis-removing material can cause enamel surface roughness and mineral content reduce and micro-hardness decreased, but the micro-hardness, calcium, phosphorus and calcium/phosphorus ratio can recover to the level before bleaching after 2 weeks.(3) Fluorosis-removing material can cause congestive in the pulp tissue of severe dental fluorosis teeth, but the change is reversible.(4) Fluorosis-removing material associated with remineralizing solution can rapidly recover tooth surface smoothness, micro-hardness and the content of calcium and phosphorus. In 2 weeks, teeth can be mineralized to a satisfactory level by saliva. |
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