锥形束CT在上颌阻生尖牙诊断中的应用

Application of Cone-Beam Computed Tomography in the Diagnosis of Impacted Maxillary Canines

目的:探讨上颌阻生尖牙在锥形束CT上的定位及其邻近切牙的根吸收情况。方法:对37例上颌阻生尖牙患者进行锥形束CT扫描,采用多平面重建(MPR)获得牙体表面的三维重建图像,观察阻生尖牙的位置。在序列纵断图像上观察阻生尖牙邻近切牙的根吸收数和吸收程度,比较侧切牙和中切牙的根吸收率、根吸收程度的构成比,分析阻生尖牙与邻近切牙有接触组和无接触组发生的切牙根吸收率,在轴位上测量阻生尖牙的滤泡大小,计算大小正常的滤泡占总滤泡数的比率。结果:14个尖牙(32.6%)近中唇侧阻生,14个尖牙(32.6%)近中腭侧阻生,其他阻生形式所占比例较小。邻近上颌阻生尖牙的侧切牙的根吸收率(52.4%)高于中切牙的根吸收率(20.9%)。有接触组中侧切牙的根吸收率(47.62%)高于无接触组(4.76%),中切牙的根吸收率(18.60%)也高于无接触组(2.33%)。阻生尖牙滤泡大小正常的占55.8%。结论:上颌阻生尖牙在锥形束CT上显示出多种不同的阻生位置,邻近上颌阻生尖牙的切牙极易发生根吸收。

Objective： To investigate the location of impacted maxillary canines and resorption of neighboring incisors with cone-beam computed tomography （CBCT）.Methods： Thirty-seven patients with forty-three impacted maxillary canines were scanned by CBCT.The three-dimensional images of impacted maxillary canines were obtained by multiplanar reconstructions （MPR） to observe the location of impacted canines.In addition,the number and extent of the neighboring incisors resorption were investigated in the sequential transaxial views.The differences in the root resorption rate between the central incisors and the lateral incisors,and the constituent ratio of extent of root resorption between central incisors and lateral incisors were analyzed.The differences in the root resorption of incisors between the exposed group,which the canines contact with the neighboring incisors,and the non-exposed group were also analyzed.Follicle size was measured in the axial views,and the rate of normal follicle was calculated.Results： Among these impactions,14 canines （32.6%） were impacted mesial-labial,14 canines （32.6%） were impacted mesial-palatal,and other impacted forms were relatively rare.Root resorption was present in 52.4% of lateral and 20.9% of central incisors.The resorption rate of lateral incisors was higher in the exposed group（47.62%） than that of the non-exposed group（4.76%）.The resorption rate of central incisors was higher in the exposed group（18.60%） than that of non-exposed group （2.33%）.The number of normal follicle with the impacted canines was 55.8%.Conclusion： The location of impacted maxillary canines varies greatly in CBCT,and resorption of neighboring incisors occurred in a high rate.