上颌尖牙-侧切牙唇侧易位的三维影像研究

Analysis of three dimensional images of labial transposition of maxillary canine and lateral incisor

目的应用锥形束CT(CBCT)研究上颌尖牙-侧切牙唇侧易位的三维特征。方法选取在南京医科大学附属口腔医院正畸科就诊并由CBCT三维影像诊断为上颌尖牙-侧切牙唇侧易位的患者40例,共计涉及46颗尖牙,在三维图像上分析易位尖牙与邻牙的关系、易位的特征,将易位尖牙分成5类。结果唇侧易位上颌尖牙均为冠唇向倾斜,近远中向以近中倾斜(80.4%)为主。在相邻中切牙、侧切牙中,10颗(21.7%)中切牙发生牙根吸收,且均累及根中1/3,8颗(17.4%)侧切牙发生重度牙根吸收。易位尖牙以Ⅲ、Ⅳ类多见,分别占总数的23.9%、39.1%。尖牙长轴越接近水平,尖牙牙尖距离正中矢状面越近,距离牙合平面越远,中切牙的牙根吸收率也越高。结论 CBCT三维定位有助于准确判断易位尖牙的位置以及与邻牙的关系,为制定治疗方案提供指导。

Obejective To discuss the three dimensional image features of labial transposition of maxillary canine and lateral incisor using cone beam computed tomography （CBCT）. Methods 40 patients （46 canines） who visited Affiliated Stomatological Hospital of Nanjing Medical University and were diagnosed as labial transposition of maxillary canine and lateral incisor with CBCT were included. Features of the canine and relationships with adjacent teeth were assessed. The transposed canines were classified into 5 groups. Results All the transposed canines inclinated labially, mesially inclination occupied 80.4%. 10 （21.7%） adjacent central incisors and 8 （17.4%） adjacent lateral incisors were observed with severe root resorption. Most of the transposed canines were defied as class 11I and class IV, whose prevalences were 23.9% and 39.1%. The closer the axis of the canine to the horizontal plane, the closer and the further cusp of canine was to the median sagittal plane and to the occlusal plane, and the higher the rate of root resorption of central incisor was. Conclusion Three dimensional positioning with CBCT helps evaluate the transposed canine position and relationships with adjacent teeth, and guide the treatment planning.