de Lima Carolina Oliveira, de Montan Julia Brito de Moura, Barbosa Ana Flávia Almeida, Antunes Bernardo Rempto, Lacerda Mariane Floriano Lopes Santos, Sassone Luciana Moura, Versiani Marco Aurélio, Silva Emmanuel João Nogueira Leal
Department of Dentistry, Federal University of Juiz de Fora, Governador Valadares, Minas Gerais, Brazil.
Department of Endodontics, School of Dentistry, State University of Rio de Janeiro (UERJ), Rio de Janeiro, Rio de Janeiro, Brazil.
Int Endod J. 2025 Feb;58(2):357-362. doi: 10.1111/iej.14179. Epub 2024 Dec 4.
To investigate the development of dentinal microcracks resulting from the progressive enlargement of the buccal canals of maxillary molars with and without the MB2 canal employing instruments with the same tip and four different tapers.
Twenty maxillary molars with (n = 10) and without (n = 10) the MB2 canal underwent micro-CT scanning. Their mesiobuccal and distobuccal canals were sequentially enlarged using nickel-titanium instruments with sizes 25/.03, 25/.05, 25/.06 and 25/.08v. Subsequent scans were conducted after each canal enlargement. The preoperative scans were coregistered with their respective datasets, and the cross-sectional images were carefully examined to identify dentinal defects. This process, conducted twice at two-week intervals, involved two examiners. Intra- and inter-examiner calibrations were validated using the Kappa index. The incidence of microcracks was reported as a percentage frequency.
The intra- and inter-examiner Kappa values were 0.85 and 0.88, respectively, indicating excellent agreement. Dentinal microcracks were detected in 1206 out of 42 975 cross-sectional image slices (2.8%). Molars with MB2 canal exhibited more slices (4.5%) than teeth without MB2 (0.9%). Every dentinal microcrack observed in the images after root canal preparation was already present in the corresponding images taken before root canal preparation.
The progressive enlargement of root canals using instruments with different tapers did not induce the formation of new dentinal microcracks in maxillary molars, regardless of the presence of the MB2 canal.
研究使用相同尖端和四种不同锥度的器械对有或无MB2根管的上颌磨牙颊侧根管进行逐步扩大时牙本质微裂纹的发展情况。
选取20颗上颌磨牙，其中10颗有MB2根管，10颗无MB2根管，进行显微CT扫描。使用尺寸为25/.03、25/.05、25/.06和25/.08v的镍钛器械依次扩大其近中颊根管和远中颊根管。每次根管扩大后进行后续扫描。术前扫描与各自的数据集进行配准，并仔细检查横断面图像以识别牙本质缺陷。该过程由两名检查人员进行，每隔两周进行两次。使用Kappa指数验证检查人员内部和检查人员之间的校准。微裂纹的发生率以百分比频率报告。
检查人员内部和检查人员之间的Kappa值分别为0.85和0.88，表明一致性极佳。在42975个横断面图像切片中检测到1206个牙本质微裂纹（2.8%）。有MB2根管的磨牙出现的切片更多（4.5%），而无MB2根管的牙齿为0.9%。根管预备后图像中观察到的每一个牙本质微裂纹在根管预备前的相应图像中就已存在。
使用不同锥度的器械对上颌磨牙根管进行逐步扩大，无论是否存在MB2根管，均不会诱导新的牙本质微裂纹形成。
