广东珠江三角洲地区人下颌第一前磨牙根管解剖形态的研究

Morphological characteristics of the mandibular first premolars in people from Pearl River Delta region in Guangdong province

目的通过普通X线片法、牙科手术显微镜下探查结合插诊断丝拍片法以及透明标本法,了解广东珠江三角洲地区人下颌第一前磨牙根管系统解剖特征。方法筛选出广东珠江三角洲地区人离体下颌第一前磨牙363颗为研究对象。将离体牙拍摄颊舌向、近远中向数字化X线片,初步判断根管数目。将离体牙开髓,采用牙科手术显微镜下观察法和离体牙透明标本法,观察并记录各牙齿的根管数目、类型。结果不同研究方法所得结果不同。普通X线片法多根管发现率为7.71%;牙科手术显微镜下探查结合插诊断丝拍片法多根管发现率为33.33%;透明标本法显示多根管发生率为34.44%,其中双根管27.82%,三根管5.79%,四根管0.83%。根管类型多样化,出现Vertuc-ci分类Ⅱ、Ⅲ、Ⅳ、Ⅴ及附加型(3-1)等。双根管的下颌第一前磨牙的髓底图特征为颊舌向直线,三、四根管下颌第一前磨牙的髓底图呈平台状。结论广东珠江三角洲地区人下颌第一前磨牙多根管出现率高,根管类型多样。牙科手术显微镜下探查法和插诊断丝拍片法结合,能够较为准确地判断下颌第一前磨牙的根管数目和类型。

Objective To investigate the morphological characteristics of the mandibular first premolars in people from Pearl River Delta region in Guangdong province using three techniques, including periapical radiographs, the radiographs with files inserted the canals and the clearing technique. Methods A total of 363 extracted mandibular first premolars were collected and numbered. Two preoperative radiographs were taken in buccolingual and mesiodistal directions respectively. After access opening, the files were placed in the canals and two other radiographs were taken. The mandibular first premolars with multi-canal system were selected and observed under dental operating microscope （DOM）. The mandibular first premolars were made transparent and were categorized using the Vertucci＇s classification. Results There were different results among the three approaches. Periapical radiographs could be used to distinguish only between one and multiple canals systems. The incidence of multiple canals was 33.33% from the radiographs with file. The mandibular first premolars had a high frequency （34.44%） of multi-canal system by clearing method. The root canal morphology of the mandibular first premolars showed great variance. The canal orifices of the mandibular first premolars with one or two canal distributed in a buccolingual line. The floor of pulp chamber of the mandibular first premolars with three or four canals was a plat form. Conclusion The mandibular first premolars have a high frequency multi-canal system and could be classified in many categories. Using DOM and radiographs with file is a useful way in judging the canal numbers and categories.