Lu Tzu-Yi, Yang Shue-Fen, Pai Sheng-Fang
Department of Dentistry, Mackay Memorial Hospital, Taiwan, Republic of China.
J Endod. 2006 Oct;32(10):932-6. doi: 10.1016/j.joen.2006.04.008. Epub 2006 Jul 13.
The purpose of this study was to assess the canal anatomy and morphology of mandibular first premolars in a Chinese population. Eighty-two extracted mandibular first premolars with intact roots were collected and stored in a glutaraldehyde solution. The teeth were embedded in clear resin and the root length was measured. The roots were resected perpendicular to the long axis at 3, 6, 9, and 12 mm from the apex. The resected root surfaces were polished, rinsed, dried, and stained with methylene blue. Digital photographs of the cross-sectional root surfaces were made at 24X. The incidence of multiple canals and varied morphology was determined by two independent examiners. The results indicated that 54% of the mandibular first premolars demonstrated a single canal. Twenty-two percent contained two canals and 18% percent had C-shaped configuration. The C-shaped root canal occurred predominantly in the 3 and 6 mm sections with one or two canals coronally. A unique finding was the circumferential canal (apical delta), which was characterized by a single canal splitting into 3 or 4 canals. The incidence of circumferential canal was 6% and occurred only in the apical 3 mm cross-sections. Identification of this unique apical canal configuration and the high incidence of multiple canals in mandibular first premolars may explain endodontic treatment failure in this tooth group.
本研究的目的是评估中国人群下颌第一前磨牙的根管解剖结构和形态。收集了82颗牙根完整的拔除下颌第一前磨牙，并保存在戊二醛溶液中。将牙齿嵌入透明树脂中并测量牙根长度。在距根尖3、6、9和12毫米处垂直于长轴切除牙根。将切除的牙根表面抛光、冲洗、干燥，并用亚甲蓝染色。以24倍的放大倍数拍摄牙根横截面的数码照片。由两名独立的检查人员确定多根管和形态各异的发生率。结果表明，54%的下颌第一前磨牙显示为单根管。22%含有两个根管，18%呈C形结构。C形根管主要出现在3毫米和6毫米的切片中，冠部有一或两个根管。一个独特的发现是环形根管（根尖三角洲），其特征是单根管分裂为3或4个根管。环形根管的发生率为6%，仅出现在根尖3毫米的横截面中。识别这种独特的根尖根管形态以及下颌第一前磨牙多根管的高发生率可能解释了该牙组根管治疗失败的原因。
