离体上颌第二磨牙牙根距根尖4mm的截面解剖研究

Study on cross-section anatomy of roots 4 mm from root apex of maxillary second molars in vitro

目的测量上颌第二磨牙牙根距根尖4 mm的截面面积,截面根管中央距牙根外壁的最短距离。方法选择30个离体上颌第二磨牙,从距根尖4 mm的部位垂直根长轴截断牙根,photoshop6.0测量牙根截面的面积以及根管中央距牙根外壁的最短距离。结果截面面积:近中颊根是(11.32±2.29)mm2,远中颊根是(7.89±1.55)mm2,腭侧根(10.50±2.82)mm2。近中颊根和腭侧根的截面面积均明显大于远中颊根(P<0.01)。牙根截面根管中央距牙根外壁的最短距离:近中颊根是(1.13±0.15)mm,远中颊根是(1.17±0.17)mm,腭侧根(1.41±0.24)mm,腭侧根的最短距离大于近中颊根和远中颊根(P<0.01)。结论上颌第二磨牙近中颊根和远中颊根距根尖4 mm的部位较细窄,在进行根管预备或桩道预备时易出现根管侧穿、牙根折。

Objective To measure the area,the shortest distance from the external surface of the roots to the center of the root canals at cross-section of the roots 4 mm from the root apex of maxillary second molars.Methods 30 extracted maxillary second molars were investigated,and then all the teeth had their roots cut off transversely to the longitudinal axis at the levels of 4 mm from the root apex.The area,the shortest distance from the external surface of the roots to the center of the root canals were calculated using photoshop6.0 by computer.Results The area of the mesiobuccal roots were（11.32±2.29） mm2,that of the distobuccal roots were（7.89±1.55）mm2,and that of the palatal roots were（10.50±2.82）mm2.The area of the mesiobuccal roots and the palatal roots were much larger than that of the distobuccal roots（P0.01）.The shortest distance from the external surface of the root to the central of the root canals of the mesiobuccal roots were（1.13±0.15）mm,that of the distobuccal roots were（1.17±0.17）mm,that of the palatal roots were（1.41±0.24）mm.The shortest distance of the palatal roots were much longer than that of the mesiobuccal roots and the distobuccal roots（P0.01）.Conclusions The positions of the mesiobuccal roots and the distobuccal roots at the roots 4mm from the root apex of maxillary second molars are narrower.Root canal perforation and root fracture is easy to occur in root canal instrumentation and post space preparation.