The Study On Complicated Root Canal System In Permanent Anterior Teeth With Cone Beam Computed Tomography

Objective: To investigate the characteristics of morphology,symmetry,age-related changes and gender difference of root canal system in permanent anterior teeth by using cone-beam computer tomography(CBCT),in order to reduce root canal leakage.Methods: A total of 6404 CBCT images of maxillary anterior teeth and 6454 mandibular anterior teeth were collected from 1103 patients(males:458,females:645).The patients were divided into group A(≤40 years)and group B(> 40 years)by the age of 40.The corresponding software of axial,coronal and sagittal section were reconstructed and observed.The number of roots and root canals,crown-root length,the types of root canal configurations,symmetry,age-related changes and gender differences were analyzed statistically.The correlation of double root canals system in mandibular central incisors,lateral incisors and canines were compared.Results: All of the maxillary anterior teeth had one root.In the mandibular anterior teeth,all of the incisors had only one root while1.66% double roots were found in canines(36/2173).Only 0.03% double root canals were found in maxillary anterior teeth(2/6404).In mandibular anterior teeth,the prevalence of double root canals was 11.25%(726/6454),the lateral incisors were highest(17.40%,374/2149),followed by central incisors(9.71%,207/2132)and canines(6.67%,145/2173).Crown-root length of central incisors,lateral incisors and canines in maxilla were measured respectively: 21.78±2.83 mm,21.28±2.71 mm and 25.29±3.18 mm.Crown-root length of central incisors,lateral incisors and canines in mandible were measured respectively:20.02 ± 1.59 mm,20.93 ± 1.39 mm and 24.32 ± 1.97 mmin.1 type Ⅱ(0.015%,1/6404)and 1 type III(0.015%,1/6404)were observed in maxillary anterior teeth,most of all were type Ⅰ(99.97%,6402/6404).In mandibular anterior teeth,type Ⅰ(88.75%,5728/6454)was most frequent type,followed by type III(7.07%,456/6454).There were no statistical significance of crown-root length(p> 0.05)in different ages in maxillary and mandibular anterior teeth.There were symmetrical distributions in the bilateral root canals of anterior teeth.The incidence of double root canals of group A(10.67%,528/4948)significantly lower than group B(13.14%,198/1507)(p=0.008).The variation of the root canal of the anterior teeth changed with ages,and the variation of the rootcanal rate increased gradually at 18-40 years,arriving highest in 41-50years(18.12%,143/789),and gradually decreased after the age of 50.The highest incidence of double root canals were all in ages of 41-50: central incisors(17.24%,45/261),lateral incisor(26.23%,69/263)and canine(10.94%,29/265)in mandible.The incidence of double root canals were significantly higher in males(13.12%,351/2676)than females(9.93%,375/3778)in mandibular anterior teeth(p=0.000).The incidence of double root canals of mandibular central incisors were positively correlated with lateral incisors and canines respectively.Conclusion: The root canal morphology of mandibular anterior teeth was complicated.The prevalence of double root canals presents symmetry,age-related changes and gender difference.CBCT was proved efficient about diagnosis and treatment in variation of root canals.