Cone-beam Computed Tomography Studied The Symmetry Of Mandibular First Molar Root Canal Aberration

Objective By using cone beam computed tomography(CBCT),it can be obtained the symmetry of its root and root canal aberration. The characteristic may provide reference for clinical treatment.Methods The research chooses 273 patients who had CBCT detection in Weifang People’s Hospital from December,2013 to July,2014. All patients have the untreated and unbroken bilateral mandibular first molars which are in good shape and full-grown. CBCT image is reconstructed by NNT version 3.0 software. Three experienced dentists observe and analyze the anatomical structure of the bilateral mandibular first molar to get the symmetry characteristics of its root number and root canal morphology by contrasting their three-dimension imagine.Results In research, 273 patients totally have 546 mandibular first molars. On CBCT image, people can find that the balance rate of the root number is 95.97%(262/273). 215 patients has two roots for the symmetrical bilateral mandibular first molar; 47 patients have distolingual roots; 7 patients have three roots on right and two roots on left while 4 patients are 4 on right and three on left. The incidence of distolingual root’s from all teeth examined is 19.23%(105/546) and there is no significant difference according to the side of occurrence( right side vs left side p>0.05). Then the balance rate of root canal morphology is 92.68%. According to root canal variability,2 roots with 2 root canals(21.25%); 2 roots with 3 root canals(37.36%); 2 roots with 4 root canals(18.32%); 3 roots with 3 root canals(10.62%); 3 roots with 4 root canals(3.30%); 3 roots with 5 root canals(1.83%).Conclusion(1) The CBCT image of bilateral mandibular first molar displays its root number symmetry is very high. The incidence of distolingual roots is also highe, and there is no significant difference according to the side of occurrence no obvious difference.(2) The CBCT images showed bilateral mandibular first molar root canal number and root canal morphology of symmetry is very high.