Objective: To investigate the association between the frequency and filling rate of lateral canals and the sealing quality in the apical third roots of the permanent teeth with failed endodontic treatments, so as to explore the failure factors of root canal therapy. Methods: Clinical records of the permanent teeth with failed endodontic treatments were collected from the Department of Endodontics, Capital Medical University School of Stomatology during a period of 2 years. The teeth were diagnosed as chronic apical periodontitis and then undergone endodontic microsurgery. The sealing quality of the apical root canal was observed by means of periapical radiographs. The surgical treatments were performed and the resected root apices were collected. The samples were scanned by micro-computed tomography and the 3D volume rendered images of the resected root apices were reconstructed. Moreover, the frequency and the filling rate of lateral canals in the apical third roots were calculated. The potential relationship between tooth position and the presence of lateral canals was evaluated. Results: Totally 89 teeth with 89 root apices met the inclusion criteria and were included in the present study. The rate of correct-filling, underfilling and overfilling was 40% (36/89), 32% (28/89), and 28% (25/89), respectively, examined by periapical radiographs. Amongst all of the 89 samples, lateral canals were found in 44 samples. The incidence of apices with lateral canals was 49% (44/89). Furthermore, 3 out of 44 samples were fully filled with material in the lateral canals, and the rest 41 samples showed no filling materials. The filling rate of the lateral canals was 7% (3/44). However, no significant difference was detected between the tooth position and the presence of lateral canals (P>0.05). Conclusions: The sealing quality of the apical third roots in permanent teeth with failed endodontic treatments was not good enough. The incidence of apices with lateral canals was high, but the filling rate of the canals was low. Further studies are needed to explore the relationship between lateral canals and the failure of endodontic treatment.
目的： 通过对根管治疗失败患牙根尖区侧支根管的检出率和充填状态进行观察，进一步了解根管治疗失败的相关因素，为临床提供参考。 方法： 选择2014年9月至2016年10月期间就诊于首都医科大学口腔医学院牙体牙髓科，因根管治疗失败需行手术治疗的慢性根尖周炎患者，利用根尖X线片观察并计算根管恰填、欠填、超填的百分比；通过根尖切除术收集患牙根尖，采用显微CT扫描及三维重建，观察并计算根尖区侧支根管的检出率和充填率，比较不同牙位根尖区侧支根管检出率的差异。 结果： 符合纳入标准的患牙89颗，根尖样本89个。术前根尖X线片显示，根管恰填、欠填和超填的检出率分别为40%（36/89）、32%（28/89）和28%（25/89）。89个样本中，44个存在侧支根管，45个无侧支根管，侧支根管检出率为49%（44/89）；其中侧支根管内有充填物的3个，无充填物的41个，侧支根管充填率为7%（3/44）。不同牙位侧支根管的检出率差异无统计学意义（P>0.05）。 结论： 根管治疗失败患牙的根管充填质量较差，根尖区侧支根管检出率较高，充填率较低。侧支根管检出率和充填状态与根管治疗失败的因果关系尚需进一步研究。.
Keywords: Endodontic surgery; Lateral canal; Root canal anatomy; Root canal obturation.