Analysis of root canal system and the consistency between maxillary first and second molars in a Taiwanese population: a CBCT study

實驗目的 在許多牙齒和根管型態的研究中發現，許多牙齒根管的變異好發於某些特定族群。在亞洲人種當中：C型根管、上顎臼齒有額外近心根管、下顎臼齒有遠心舌側牙根的比率，似乎比其他人種來的高。在文獻回顧中上顎臼齒的根管治療臨床上失敗率很高，被歸因於其複雜的根管型態，本研究的目的是利用錐狀射束電腦斷層(CBCT)來分析台灣人口中，上顎第一大臼齒和第二大臼齒的根管系統的型態和彼此間的相似性、對稱性、和關聯性。 實驗方法 本研究蒐集了從2014年1月到2014年12月在台大醫院牙科部有照射CBCT影像的病人，符合條件的病人一共有519位。由兩位根管專科醫師和一位放射師來判讀這1741顆上顎大臼齒的影像，和分析兩顆上顎大臼齒彼此間的關聯性。 實驗結果 在台灣人口中，上顎第一大臼齒最常見的型態是三牙根四根管(3R4C)，而上顎第二大臼齒最常見的型態則是三牙根三根管(3R3C)。在356位具有兩個上顎第一大臼齒的病人中，兩側的上顎第一大臼齒根管型態對稱的比率是87.36%；在392位具有兩個上顎大臼齒的病人中，兩側上顎第二大臼齒對稱的比率是79.85%。在相鄰兩顆上顎第一和第二大臼齒的組別中(右側375組，左側388組)，右側上顎第一大臼齒和上顎第二大臼齒根管具有相似性的比率是53.07%，左側組別則是52.58%。兩側上顎第一大臼齒同時具有近心頰側第二根管(MB2canal)的比率是77.8%，在雙側上顎第二大臼齒則是35.97%。在110位雙側上顎第二大臼齒同時具有近心頰側第二根管的病人中，他們的雙側上顎第一大臼齒也同時具有近心頰側第二根管的比率幾乎是100%。 結論 上顎第一大臼齒比上顎第二大臼齒有更高的3牙根四根管(3R4C)的盛行率。在同一位病人中，上顎同質性的牙齒根管型態的對稱性高於相鄰兩顆上顎大臼齒。術前分析CBCT影像和了解根管可能的關聯性，可以有效率的提升根管治療的成功率。Objectives The aim of this study was to use cone-beam computed tomography (CBCT) to analyze the morphology and similarity / symmetry of root canal systems in the maxillary first and second molars in Taiwanese. Materials and methods A total of 519 patients in the dental department of NTUH from January 2014 to December 2014 were enrolled. Overall, CBCT images of 1741 maxillary molars were blindly examined by two endodontists to analyze the correlation of root canal systems between the first molars and second molars as well as the bilateral first or second molars. Results The most common type in Taiwanese maxillary first molars is 3R4C (3 roots/4 canals), whereas in maxillary second molars is 3R3C.The symmetry of root canal system in bilateral maxillary first and second molars were found in 87.36% and 79.85%,respectively. The similarities of root canal system in adjacent maxillary first and second molars were 53.07% in right side and 52.58% in left side. The concurrence of MB2 canal in bilateral maxillary first molars is 77.8%, whereas is 35.97% in maxillary second molars. In the 110 patients MB2 canal in bilateral maxillary second molars, the chances of bilateral MB2 canals in their maxillary first molar is almost 100%. Conclusions Maxillary first molars have higher prevalence of 3R4C root canal system than maxillary second molars. The symmetry and similarity were higher in bilateral maxillary homonym molars than in adjacent maxillary molars. These information and assessing CBCT images in advance provide a totally understandings of the whole root canal system, and improve the endodontic treatment outcome efficiently