目的:观察地塞米松(DXM)对SD大鼠第三磨牙进行阻萌的效果.方法:刚出生5d和出生21 d的SD大鼠各12只各分为3组(n=4),每组一侧第三磨牙区域注射0.1ml浓度不等(1.94×10-3 mmol/L、1.94×10-4 mmol/L、×10-5 mmol/L)的DXM,对照侧注射0.1ml生理盐水.5d的SD大鼠在21 d和43 d分2次处死,21 d的SD大鼠在43、52 d处死,然后对成功阻萌的21 dSD大鼠高浓度组实验侧和对照侧进行大体观察、X线、HE染色等进行对比研究.结果:PN21 d高浓度DXM组SD大鼠实验侧第三磨牙均未能正常萌出,对照侧均正常萌出;X线检测显示其实验侧第三磨牙仅有牙冠形成,未能形成明显牙根;HE切片显示其根发育障碍.结论:在牙发育钟状末期可以通过地塞米松的局部注射阻萌SD大鼠的第三磨牙.%Objective:To observe the effect of dexamethasone(DXM) in the prevention of the development of third molars in SD rats.Methods:12 SD rats of 5 days old(PN 5 d) and 12 SD rats of 21 days old(PN 21 d) were respectively divided into 3 groups(n =4).The rats were injected with 0.1 ml DXM at 1.94 × 10-3 mmol/L,1.94 × 10-4 mmol/L and 1.94 × 10-5 mmol/L respectively into the experimental side,and 0.1 ml normal saline into the control side.PN5d SD rats were respectively killed 21 d and 43 d after injection.PN 21 d SD rats were killed 43 and 52 d after infecion.The PN 21 d SD rats injected with the highest concentration of DXM were the successful models of development prevemion of their third molars in experimental side.The tissue samples were subjected to general observation,radiographic and HE staining examination.Results:After injection,in the highest concentration groups,third molars on the experimental sides of PN 21 d SD rats were not erupted,the control side showed normal eruption.X-ray examination showed crown formation on the experimental sides of the third molars,but without root formation.HE biopsy revealed disorder of root development.Conclustion:DXM with certain concentration injected into local area in late bell stage can prevent tooth development.
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