Abstract: Objective: To compare the differences between Cone-beam computed tomography (CBCT) and Radio visio graphy (RVG) technique in evaluating root canal morphology of mandibular incisors. Methods: One hundred and one extracted mandibular incisors were used in this study. Labial-lingual, mesial-distal RVG projection and CBCT scan at the HZ DS mode were done. The number of root canals, the Vertucci's classification, the calcification of root canal and the position of apex were evaluated. A mathematical model was established to calculate the angle of x-ray tube inclination. Results: Thirty-six teeth were found to have a second root canal in mesial-distal RVG images, and 30 incisors were considered to have two root canals in CBCT images. There were significant differences between CBCT and RVG as to the number of root canals and Vertucci's classification(P<0.05), but insignificant differences with regard to calcification of root canal and the position of apex. In the 30 incisors with two root canals, when the distance between the labial and lingual root canal (LaL) ranged between 0 and 1.5mm, 85.7% was Vertucci type III; when LaL ranged between 1.5 and 2mm, 66.7% were Vertucci type IV and V. If the distance pre-



基金项目 江苏省自然科学基金(编号:BK20150089,BK20141083)
南京市医学科技发展项目(编号:ZKX14049,YKK15116)
南京市卫生青年人才(编号:QRX11264)
作者简介 计艳(1982~ ),女,江苏溧阳人,主治医师,硕士,主要从事口腔疾病的预防工作。
*通讯作者 林梓桐,E-mail:linzitong710@163.com
sent on the RVG images was set to 1mm, the projecting angle should be from 26.6° to 45.0°for the teeth with LaL ranged between 1 and 2mm, and from 45.0° to 84.3°with LaL ranged between 0.1 and 1mm. Conclusion: There were significant differences between CBCT and RVG for evaluation of the number of root canals and Vertucci's classification but insignificant differences for evaluation of calcification of root canal and the position of apex. It was more practical to do mesial-distal projection mandibular incisors with LaL ranged between 1 and 2mm.

Key words: Cone-beam, computed, tomography, Radio, visio, graphy, Mandibular, incisors, Root, canal, morphology