| Backgroud: The incidence of second mesiobuccal in maxillary first molar is high.The MB2 canal is hard to be visualized in the buccolingual view of intraoral radiographs,and its orifice is often covered by secondary dentin.Therefore,missing to deal with the canal may lead to the failure of root canal treatment.To date,with the application of Cone-beam computed tomography,clinicians are more familiar with the internal anatomy of the teeth and more accurate in the diagnosis of difficult canals.However,CBCT is not yet a routine diagnostic method for endodontic patients.This study is focused on the anatomic morphology of the mesiobuccal root canal,the incidence of the second mesiobuccal root canal,and the relationship between the presence of an MB2 canal and the distribution of mesiobuccal,distobuccal and palatal canal orifices on the pulpal floor,aiming to provide help in the process of treatment.Introduction: The purpose of this study was to investigate the anatomic morphology of the mesiobuccal root canal,the incidence of the second mesiobuccal root canal,and the relationship between the presence of an MB2 canal and the distribution of mesiobuccal,distobuccal and palatal canal orifices on the pulpal floor with the aid of cone-beam computed tomographic(CBCT)technology.Methods: A total of 548 CBCT images were randomly selected and analyzed.The name,sex,side and age of each patient were recorded.The interorifice distances(ie,the length of a line between the center point of any 2 orifices)at the pulpal floor level were measured using Mimics 10.01 software(Image Works,Materialise,Belgium).The Pearson chi-square test was used to assess the association between the incidence of MB2 canals and the patients’ sex,side and age.Receiver operating characteristic curve(ROC)was used to evaluated the diagnostic accuracy of using the ratio of MB1-P to DB-P for predicting the presence of an MB2 canal.The optimal threshold was determined according to sensitivity,specificity,positive predictive value(PPV),and negative predictive value(NPV).Results: In 1008 maxillary first molars(548patients),the majority of 3-rooted maxillary first molars showed 2 root canals(85.4%)in the mesiobuccal root.The incidence of MB2 canals had no statistically significant difference between the left and right sides(P >.05),a higher incidence of MB2 canals was detected in male patients than in females(P<0.05).With regard to the age of patients,a statistically significant difference was found among the 5 age groups(16-25 y,26-35 y,36-45 y,46-55 y,>55y)(P<0.05).Receiver operating characteristic curve analysis showed a high diagnostic accuracy(the area under the receiver operating characteristic curve = 0.92)of using the distance ratio of the interorifice distance between the main mesiobuccal and the palatal root canal orifices to the interorifice distance between the distobuccal and the palatal root canal orifices to predict the presence of an MB2 canal.A larger distance ratio(>1.26)indicated a highly probable existence of an MB2 canal.In this study,no molar presented an MB2 canal with a distance ratio of less than 1.16,whereas all molars with a ratio greater than 1.37 presented an MB2 canal without exception.A Bland-Altman scatterplot showed great agreement between the distances of the main mesiobuccal and the distobuccal canal orifices and the secondmesiobuccal and the distobuccal canal orifices.Conclusions: The presence of an MB2 canal is related to the distribution of other three main(mesiobuccal,distobuccal and palatal)canal orifices on the pulpal floor.Understanding the incidence of MB2 canals and the distribution pattern of canal orificesmay help clinicians to quickly identify and locate MB2 canals. |
PDF Full Text Request