第一恒磨牙根尖孔解剖及其与初锉的关系

目的探讨上、下颌第一恒磨牙根尖孔的解剖及其与初锉尖端的适合性。方法上、下颌离体第一恒磨牙各30颗,冠方预展后确定初锉号数,立体显微镜下观察根尖孔的数目、根尖表面主根尖孔的位置和形态,测量主根尖孔和距根尖孔1mm、2mm、3mm处根管横断面的最大径及最小径。结果78.1%的根管有一个根尖孔;主根尖孔54.8%位于根尖顶,呈椭圆形者占92.5%;主根尖孔和距根尖孔1mm处管径相当,距根尖孔1mm、2mm、3mm处根管的最大径和最小径依次递增;初锉尖端直径比距根尖孔1mm处根管最小径稍小,比最大径平均小三个锉号。结论以根尖狭窄部最小径确定的初锉为基线进行根管机械预备,根管壁的清创质量可能受到影响。

The relationship between the apical anatomy of first permanent molars and initial apical file

Objective To investigate the apical anatomy of maxillary and mandibular first permanent molars and its adaptability to the tip of initial apical file (IAF).Methods This investigation was carried out on 30 maxillary and mandibular first permanent molars, respectively. Post-preflaring IAF size was determined and the number, location, form of the foramen were observed with stereomicroscope. Canal diameters were measured at 0, 1, 2, and 3 mm from the apical foramen.Results A total of 78.1% of root canals had one apical foramen; 54.8% of main apical foramen existed at the apex, and 92.5% was oval. The diameters of apical foramen corresponded with those at 1mm from it. Canal diameters increased gradually at 1, 2, and 3mm from the apical foramen. The tip diameters of the IAF were slightly smaller than the canal minimal diameters at 1mm from apical foramen, and were three sizes smaller than the maximal diameters.Conclusion The IAF based on the canal minimal diameters can't adequately show working width, so root canals debridement is inadequate.