Study On The Application Of Two Classification Systems To The Mandibular First Molars

Objective Cone-beam computed tomography(CBCT)images were retrospectively analyzed to observe the root number and canal morphology of mandibular first molars.Vertucci classification system and Ahmed classification system were used to classify the root canal morphology.To determine the common root canal morphology and anatomical variation types.It provides certain reference for future clinical research and work.Method CBCT images of 400 patients(a total of 800 mandibular first molars)who met the inclusion criteria were selected in chronological order.The CBCT images of mandibular first molars were analyzed and evaluated.The number of root and canal morphology of the patient were recorded in detail.According to Vertucci classification system and Ahmed classification system,the number of root was identified and the root canal morphology was classified.Chi-square test was used to compare the incidence of distal tongue root in mandibular first molars.The bilateral correlation of distal tongue root was analyzed by Pearson correlation coefficient.Results 1.Among the 800 mandibular first molars,222 were the three mandibular first molars,and the incidence of distal tongue root and distal tongue root was 27.8%(222/800).The incidence of distal tongue root and distal tongue root on both sides of the right mandibular first molars(31.0%)was higher than that on the left(24.5%),but the difference of the incidence of distal tongue root of the right mandibular first molars was not statistically significant(c~2=3.045,P=0.081>0.05).2.Vertucci based on classification,type IV root canal in the double root and three are the most common in the mandibular first molar mesial roots,were 63.5%(367/578),87.8%(195/222)type I root canal in the double root of the mandibular first molar far far buccal root and root of the mandibular first molar root and far more common in your tongue,were 61.2%(354/578),100%(222/222),100%(222/222)on the basis of classification of Ahmed,the most common of mandibular first molar root and root canal morphology of ~2M~2D~1,43.1%(249/578)and ~3M~2DB~1DL~1,87.8%(195/222).Conclusion 1.The distal tongue root is a common type in the anatomical variation of the mandibular first molar,with a high incidence in females and a bilateral correlation.2.The root and canal morphology of mandibular first molars were dominated by proximal single root (type 2-2),distal single root(type 1-1)and proximal single root(type 2-2),and distal double root(type 1-1 of distal tongue).3.Compared with Vertucci classification system,Ahmed classification system can describe the morphology of root and canal more accurately and practically,which is more conducive to statistics and analysis of data,and can be applied in clinical and research.4.CBCT can effectively evaluate the morphology of root and canal because of its three-dimensional imaging characteristics.