镍钛螺簧牵拉大鼠第一磨牙向近中移动:正畸牙移动模型

Mesial movement of the rat molars using Ni-Ticoil spring: a model of orthodontic tooth movement

背景:在有关正畸牙移动的实验中,动物模型的建立是关键,其中力值的选择、支抗的控制对实验结果的影响很大。目的:在综合考虑各种因素的情况下,建立一个较完善的正畸牙移动动物模型。方法:在20只Wistar大鼠上颌两个切牙牙根中部水平钻洞,用0.3 mm直径结扎丝从洞中穿过,将牙槽骨、两个切牙结扎在一起,将右上颌第一磨牙以0.2 mm直径结扎丝结扎,随机分为4组,在切牙和第一磨牙间分别置10,25,50 g Sentalloy镍钛螺簧,以切牙为支抗,拉第一磨牙向近中移动,以不加力的为对照组。加力后14 d苏木精-伊红染色观察第一磨牙牙体牙髓变化,并使用软件测量计算牙本质吸收相对深度。结果与结论:10 g镍钛螺簧组牙骨质不规则吸收,压力侧牙周膜间隙变窄;25 g镍钛螺簧组压力侧可见牙骨质及牙本质不规则吸收;50 g镍钛螺簧组牙根可见明显的吸收,深达牙本质层。10 g螺簧组牙本质吸收相对深度与对照组相比差异无显著性意义(P>0.05),其他各组之间牙本质吸收相对深度差异均有显著性意义(P<0.05)。说明在大鼠两个中切牙牙根中部及牙槽骨处钻洞并用结扎丝结扎,使两个中切牙与牙槽骨成为一个整体,共同作为支抗,采用镍钛螺簧拉第一磨牙近中移动,可建立稳定、科学、可靠的正畸牙移动的动物模型。10 g力是大鼠第一磨牙近中移动所需的合适力值。

BACKGROUND：The establishment of model is very crucial in the orthodontic tooth movement experiment. The selection of force and control ing of anchorage may greatly affect experimental results. OBJECTIVE：To establish an animal model for orthodontic tooth movement. METHODS：Twenty Wistar rats were included in this study. The root of incisor teeth at upper jaw was dril ed and then threaded with a ligature wire （0.3 mm diameter）, therefore the alveolar bone and two incisor teeth were ligated. The first molar at right upper jaw was also ligated using a ligature wire （0.2 mm diameter）. The experimental teeth were randomly divided into four groups. A Sental oy closed-coil spring （10 g, 25 g, 50 g） was placed between the maxil ary incisors and the maxil ary first molar, respectively. Taking the incisor as the anchorage, the molars were given a mesial movement, and control group received no force. On day 14, the dental pulp, dentin and enamin resorption was analyzed with Image-Pro Plus software. RESULTS AND CONCLUSION：A light force （10 g Ni-Ti coil spring） produced irregular enamel resorption and narrowed periodontal membrane space, whereas heavy force （25 g Ni-Ti coil spring） produced irregular dentin and enamel resorption, even heavier force （50 g Ni-Ti coil spring） produced apparent resorption at dental root, which affected the dentin. No statistical difference of the relative depth of dentin resorption was found between the 10 g group and the control group （P〉0.05）. The data between other groups showed statistical y significant differences （P〈0.05）. The mechanical union of the incisors and the mandibular bone efficiently prevents the continuous eruption of the upper incisors, which maintains the anchorage stability. Using Ni-Ti coil spring, a stable, scientific and reliable model of orthodontic tooth movement can be established through mesial movement of the first molars. The optimal force of 10 g is used to move the rat first molar mesialy.