The Influence of Missed Canals on the Prevalence of Periapical Lesions in Endodontically Treated Teeth: A Cross-sectional Study

Introduction: Untreated root canals may have a direct impact on the prognosis of root canal treatment. The objective of this cross-sectional study was to evaluate the association of missed canals with periapical lesions in endodontically treated teeth. Methods: One thousand one hundred sixty preexisting cone-beam computed tomographic scans from 8 different health centers were assessed between January 2018 and December 2018 by 5 independently calibrated observers. Two thousand three hundred five endodontically treated teeth were identified in a sample of 20,836 teeth (27,046 roots). All endodontically treated teeth were evaluated for the presence or absence of missed root canals and periapical lesions. The z test for proportions was used to analyze differences between groups, and an odds ratio was calculated in order to analyze the association between missed canals and lesions. P < .05 was considered statistically significant. Results: The prevalence of missed canals was 12.0%, and teeth with untreated canals were associated with periapical pathology in 82.6% of the cases. The root presenting with the highest percentage of missed canals (62.8%) was the mesiobuccal root of the maxillary first molar, being associated with periapical lesions in 75.2% of cases. Maxillary molar mesiobuccal roots presenting with a missed canal were 3.1 times more likely to be associated with periapical pathology than maxillary molars with all canals identified and treated. Conclusions: The association between untreated root canals and the presence of periapical lesions noted in the present study shows that missed canals have a significant impact on treatment prognosis.