Physical morphology of the root canal taper in the apical region of human permanent first morlars / 北京大学学报(医学版)

ABSTRACT

Objective:To investigate the physical morphology of the root canal taper in human maxillary and mandibular permanent first molars.Methods: Forty maxillary and 44 mandibular extracted human permanent first molars were investigated.The roots were dissected transversely from their apical foramen vertical to the long axis of the root,and 1-mm-thick serial sections were made.The root apex side of each section was observed with a stereomicroscope at 30? magnification.The maximum and minimum canal diameters were measured at 0,1,2,and 3 mm from the apical foramen.The physical canal taper in the apical section was calculated.Results: 47.5%-60.0% of the narrowest diameter of root canals were present at the foramen,and 25.0%~42.5% located at the level of 1 mm from apical foramen.Almost all physical configurations of root canals in 3 mm apical region showed a bottleneck-like taper.Canal dia-meters increased rapidly at 1-2 mm with the biggest taper,and the taper had a bigger variance(0.07-0.35).The ring of shrunken bottleneck was formed at the level of 1 mm from apical foramen.The taper of canal in maximal diameter was larger than the one in minimal diameter.Conclusion: The physical morphology of bottleneck-like taper in apical canal was helpful to locate the canal apical stop in root canal treatment.