Background and Aim: The heightened incidence of endodontic failure in maxillary first molars (MFMs) has been attributed to their morphological complexities notably evident in the mesiobuccal (MB) root canals. Given the absence of data on the internal anatomy of MFMs among the Iranian population, this research aimed to eval-uate the root canal system (RCS) morphology of MFMs utilizing cone beam computed tomography (CBCT).
Materials and Methods: In this descriptive retrospective study, internal anatomy of 314 MFMs was evaluated on CBCT scans taken from patients attending a dentomaxillofacial radiology clinic. CBCT scans of MFMs were retrieved and interpreted by observers for their internal anatomy. Fisher’s Exact test, Chi- Square test, independent-samples t-test and one-way ANOVA were used to analyze data using SPSS 26 software.
Results: Of a total of 314 MFMs evaluated, 97.5% [95% CI: (95.7%, 99.2%)] had three roots and 67.2% [95% CI: (62.0%, 72.3%)] had four root canals; the difference in number of canals was not significant between males and females (P=0.130). In 68.4% of cases, MFMs on both sides exhibited morphological similarity. Accessory canals were more commonly encountered in individuals between 40 to 60 years of age in all roots except for MB root; whereas in MB root, ac-cessory canals were more commonly seen in 20-40 year olds. Vertucci’s types II, I and III were the most common canal types in evaluated MB roots. Vertucci’s type I was the most common type in distobuccal (DB) and palatal (P) root canals.
Conclusion: More than half of the MB roots of MFMs had two root canals. CBCT scans could give valuable anatomical information prior to endodontic treatments. Some ana-tomical features varied according to the patient’s gender and age.