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BACKGROUND Invaginated teeth pose greater challenges in clinical management because of their complex configuration. With advancements in equipment and materials, such as the dental operation microscope, cone-beam computed tomography and mineral trioxide aggregate, the preservation rate of type III dens invaginatus could be greatly increased. CASE SUMMARY This case report presented a 31-year-old woman with complaints of spontaneous swelling and pain in the right maxillary lateral tooth. With the aid of cone-beam computed tomography, type III dens invaginatus with apical periodontitis was diagnosed and confirmed. Three-visit endodontic treatment was performed. In the first visit, the invagination was carefully removed under the dental operation microscope, and chemomechanical preparation was done. In the second visit, mineral trioxide aggregate apical barrier surgery was performed in this tooth. In the third visit, the canal was finally obturated with thermoplastic gutta-percha to recover the crown morphology. A 26-mo follow-up revealed a satisfied outcome both in the radiographic and oral examinations. CONCLUSION In this case, removal of the entire abnormal structure provided great convenience for the follow-up treatment. When confronted with the same clinical case in the future, we can take a similar approach to address it.

OBJECTIVES A thymic epithelial tumour is the most common primary tumour in the anterior mediastinum of adults. A few retrospective studies compared the short-term outcomes between robotic-assisted thymectomy (RAT) and video-assisted thymectomy (VAT). So, it is necessary to conduct a meta-analysis to further compare these 2 surgical techniques. METHODS EMBASE, Medline and Web of Science were used. Thesaurus terms and medical subject headings were used in Medline and EMBASE, respectively. The Newcastle-Ottawa scale was used for grading because the included studies were all case-control studies. RESULTS Nine studies were included in the meta-analysis with a total of 723 patients, including 315 patients in the RAT group and 408 patients in the VAT group. The meta-analysis [odds ratio (OR) 0.24, 95% confidence interval (CI) 0.06–0.94; P = 0.041], indicating that RAT yielded a significantly lower rate of conversion compared with VAT. Duration of drainage with RAT was significantly less than that with VAT (weighted mean difference = −1.10; 95% CI −1.98 to −0.22; P = 0.014). The pooled analysis (weighted mean difference = −103.6; 95% CI −199.21 to −7.98; P = 0.034) suggested that patients in the RAT group had less drainage than those in the VAT group. The recurrence rates in both groups were comparable (OR 0.19, 95% CI 0.03–1.20; P = 0.078). CONCLUSIONS RAT has advantages over VAT in terms of short-term outcomes such as shorter duration of drainage, less total drainage and a lower rate of conversion. The recurrence rate was comparable between the 2 techniques. Therefore, RAT could be considered as an alternative treatment for diseases of the thymus.

The purpose of this study was to investigate the incidence and location of the second mesiobuccal (MB2) root canal of the maxillary first molar and the relationship between the presence of an MB2 canal and the distribution of canal orifices on the pulpal floor with the aid of cone-beam computed tomographic (CBCT) technology.A total of 1008 maxillary first molars (548 patients) were randomly selected and analyzed through CBCT imaging. The association between the incidence of MB2 canals and potential impacting factors including sex, side, age, and the distribution of the main root canal orifices on the pulpal floor was explored. 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 (ImageWorks, Materialise, Belgium).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) but had a significant association with the patients' sex and age (P .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 second mesiobuccal and the distobuccal canal orifices.Understanding the incidence of MB2 canals and the distribution pattern of canal orifices on the pulpal floor may help clinicians to quickly identify and locate MB2 canals.