RESUMO
OBJECTIVES: To evaluate the prevalence of missed canals in endodontically treated maxillary molars through cone-beam computed tomography (CBCT) images and to verify their association with the presence of periapical lesions. MATERIAL AND METHODS: Three oral radiologists evaluated 633 maxillary molars in CBCT exams regarding number of roots, number of root canals, number of missed canals, anatomic identification of missed canals, presence of periapical lesions, and root location of the periapical lesions. Data were statistically analyzed at a 5% significance level. RESULTS: Descriptive statistical analysis showed that among 395 first molars, 218 had at least one missed canal, and 186 (46.5%) had a missed canal and periapical lesion simultaneously. Of these, 72.4% (134) of the missed canals were only mesiobuccal 2 (MB2). Among 238 s molars evaluated, 121 presented at least one missed canal, and 104 (43.6%) had a missed canal and periapical lesion simultaneously. Of these, 81.7% (85) of the missed canals were only MB2. The chi-squared test showed an association between the presence of missed canals and periapical lesions for 1st and 2nd maxillary molars. Teeth that presented a missed canal showed an odds ratio (OR) of 2.57 (p < 0.0001) of being associated with a periapical lesion. Missed canal occurrence was positively related to the number of root canals (z = 13.06, p < 0.0001), meaning when the number of root canals is higher, there is a higher probability of missed canal occurrence. According to the model calculated prediction, for a one-unit increase in the number of canals, the probability of missed canals increases by 4.22%. CONCLUSIONS: It was concluded that MB2 was the most frequently missed canal, associated with the presence of periapical lesions in endodontically treated maxillary molars. CLINICAL RELEVANCE: Professionals' negligence of anatomical root variations has been contributed to the high prevalence of missed canals, leading to failures in endodontic treatment. Their association with periapical lesion occurrence emphasizes the importance of correct detection and instrumentation of these canals.