SD大鼠第三磨牙阻萌的研究

Prevention of the development of third molars in SD rats

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5 d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0.1 ml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0.1 ml生理盐水。5 d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 d SD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:PN 21 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 nonnal 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 prevention of their third molars in experimental side. The tissue samples were subjected to general ob- servation, 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 for- marion on the experimental sides of the third molars, but without root formation. HE biopsy revealed disorder of root development. Con- clustion： DXM with certain concentration injected into local area in late bell stage can prevent tooth development.