Root Canal Morphology Of Maxillary And Mandibular First Molars Analyzed By Cone-beam Computed Tomography In Chinese Han Adolescents Of Luzhou Area

Objective:The aim of this research is to study on the maxillary and mandibular first molars in Chinese han adolescents of Luzhou area by retrospective analysis of a large number of cone-beam computed tomography(CBCT)images.Determining the anatomical characteristics of root canal system in Chinese han population to provide the basis theory to improve on the local success rate of root canal therapy,and provide reference data for Chinese research on root canal system.Methods:A total of 486 subjects with healthy,untreated,well-developed maxillary and mandibular first molar teeth who required CBCT examinations as part of their dental diagnosis and treatment in dental hospital of Luzhou medical college were enrolled in the present study.The number of root canals,and the root canal configuration based on Vertucci's classification were determined.All data were recorded which include number and configuration of root canals,then analyzed anatomical characteristics of root canal system between different gender and sides and established the symmetry in root canal configuration between right and left sides in the same patient,and analyzed the correlation in the same patient who have more root canals between maxillary and mandibular first molars.Count data was expressed as percentage,the correlations for occurrence of the trait were analyzed by the Pearson contingency coefficient correlation test,and all the data were statistical analyzed by SPSS for windows(16.0).Use Chi-square tests to analyze the differences between gender,sides and root canal configuration and Pearson contingency coefficient.Results:?.Most maxillary first molars had three separate roots,with a lower incidence of one root.Four root canals had the highest incidence of 65.95%,followed by three root canals with incidence of 29.32%,the incidence of five root canals and one canal were 4.42%and 0.31%respectively.No significant sex-related differences were shown for their prevalence,and there was no statistically significant difference between right and left side;?.71.91%of examined mandibular first molars had 2 roots,while 27.78%had 3 roots,0.31%occurred C-shaped canals.The incidence of four root canals was 49.07%,at the same time the incidence of three root canals was 47.43%,two root canals and five root canals were rarely occurred,the incidences were 2.37%and 0.82%respectively.There was no statistically significant difference both between different gender(male and female)and different sides(right and left);?.The root canal configuration of mesiobuccal root of maxillary first molar was complex,it had more variation.Rank the root types according to higher incidence,type IV(32.51%),I(30.86%),?(17.44%),?(8.46%),?(6.39%),?(3.20%),2-3-2,2-3-1.Overall,the prevalence of second mesiobuccal canal(MB2)of the maxillary first molar was 67.91%.Most distobuccal root of maxillary first molar had showed type I,others were type ?,?,?,?,?,?,2-3-2.Palatal root of maxillary first molars appeared simple canal configuration,almost all the palatal root canals were type ?,occasionally occurred type IV.There was no statistically significant difference both between different gender and different sides;?.The prevalence of double root canals in the mesial root of the mandibular first molars was 93.51%%.Rank the root types according to higher incidence,type ?,?,?,?,?,?,2-3,3-2,type IV had the highest incidence of 87.41%.In the distal roots,the incidence of two root canals was 55.79%.Among the mandibular first molars with two roots,Rank the root types according to higher incidence,type ?,?,?,?,?,?,?,type ? had the highest incidence of 65.24%,followed by type I with incidence of 29.04%.All the distobuccal and distolingual root of mandibular first molars which had three roots had showed type ?.There was no statistically significant difference both between different gender and different sides;?.The mesiobuccal root of maxillary first molars were found to be symmetrical in 71.07%,while the distobuccal and the palatal root had showed symmetry in 97.73%and 99.79%respectively.The distolingual root of mandibular first molars had showed symmetry in 65.64%.The mesial root of mandibular first molars which had two roots were found to be symmetrical in 91.28%,whereas the distal roots of mandibular first molars which had two roots were symmetrical in 91.9%.The mesial root of mandibular first molars which had three roots had showed symmetry in 82.24%,About 96.26%of the distobuccal root and 100%of the distolingual root showed symmetry.No significant sex-related differences were shown for their prevalence;?.Pearson's correlation analysis of Maxillary first molars had more than three root canals while mandibular first molars had showed more than three root canals revealed a certain extent correlation(P<0.01),the result of the r ranged from 0.339 to 0.555,the average value was 0.399.Conclusions:?Among the Chinese han adolescents of Luzhou,the incidence of a second canal in the mesiobuccal root of maxillary first molars and the distal root of mandibular first molars were in the high incidence,the dentists should pay more attention to probe the second root canal;?.Among the Chinese han adolescents of Luzhou,both maxillary first molars and mandibular first molars had showed a high symmetry,as well as maxillary and mandibular first molars,and had a certain extent correlation in the occur of multiple canals,this characteristic was useful for the dentists to probe the extra canal;?.No significant sex-related and side-related differences were shown for their prevalence of Chinese han adolescents of Luzhou;?.CBCT is a useful tool for endodontic diagnosis and treatment in dental clinic.