Prevalence and Distribution of the Middle Mesial Canal in Mandibular First Molar Teeth of the Kerman Population: A CBCT Study

Purpose. Missed additional canals are one of the most important reasons for RCT failures in molar teeth. This study aimed to determine the prevalence and distribution of middle mesial canals in mandibular first molars of the Kerman population. Materials and Methods. A retrospective study was performed on de-identified cone beam image sets from 3 private radiology centers in Kerman. A total of 100 mandibular first molars from 62 patients (mean age 32 years) were included. Information regarding the patient's age and gender, the location of teeth, and the presence or absence of a MMC and also a second distal canal in MMC cases was recorded in an Excel table. Data were analyzed using SPSS software (IBM-USA). Results. The overall prevalence of MMCs in the mandibular first molars was 8.1% (10.0% in females and 6.3% in males). More cases of MMCs were seen on the right side (12.2%) than the left side (3.4%). One case of bilateral MMCs combined with bilateral second distal canals in the mandibular first molars was seen in a 26-year-old female. A further case of bilateral MMCs was found in a 32-year-old male but with single-canal distal roots on both sides. Conclusion. The overall prevalence of MMCs in the Kerman population (8.1%) is at the lower end of the reported range of the international literature (0.26% to 53.8%). In the cohort examined in this study, mid mesial canals were more prevalent in females and on the right side. There was no definite relationship between MMCs and second distal canals in the mandibular first molar teeth in the same subject. MMCs may be unilateral or bilateral. Careful exploration of the pulpal floor between canal orifices is essential to prevent missing the MMC, as this would cause undesirable clinical outcomes.