Cross-sectional study on the incidence of two mesial canals joining at the apex of the Mesiobuccal root in mandibular first molars in a North Jordanian Population

Methods: A cross-sectional study was conducted at Princess Haya Bint Al-Hussein Military Hospital, Jordan.  Between November 2025 and April 2026, 98 adult patients (18-65 years) in need of primary endodontic treatment of mandibular first molars were randomly allocated to the single-file or multi-file technique. Clinical and radiographic examinations including periapical radiographs and limited field-of-view cone-beam computed tomography (CBCT) for ambiguous cases were performed. Canal configurations were classified according to Vertucci criteria. Statistical analysis was performed using SPSS v26, with chi-square tests, t-tests and logistic regression (p<0.05).
Results: Of 98 teeth (mean age 37.4±13.1 years; 52% male), 67.3% (n=66) had two mesial canals. Among these, 26.5% (n=26) had Vertucci Type II configuration (two canals joining at the apex), and 40.8% (n=40) had Vertucci Type IV (two separate canals). Younger patients (<40 years) had significantly higher prevalence of merged canals (34.0% vs. 18.8%, p=0.03). No significant gender difference was observed (p=0.58). CBCT showed superior detection sensitivity (91%) compared to periapical radiography (69%). Merged canals required longer instrumentation time (9.4±1.9 vs. 7.6±1.5 minutes, p=0.01).
Conclusion: The prevalence of Vertucci Type II configuration in mandibular first molars among this North Jordanian cohort was 26.5%. Younger age was associated with higher prevalence. Advanced diagnostic modalities like CBCT improved the detection rates greatly. These results support endodontic treatment planning for the population of Jordan