Retrospective Assessment of Healing Outcome of Endodontic Treatment for Mandibular Molars with C-shaped Root Canal

Abstract

Background:
C-shaped root canal systems in mandibular molars present considerable anatomical and clinical challenges that can adversely affect endodontic success. Their complex configurations, featuring fins and anastomoses, often complicate debridement, disinfection, and obturation, resulting in variable healing outcomes. Comprehensive retrospective evaluations are essential to understand the prognostic determinants influencing treatment success.

Objective:
To retrospectively assess the healing outcomes of endodontically treated mandibular molars with C-shaped root canal systems and to identify key clinical and procedural factors associated with successful periapical healing.

Methods:
A total of 126 C-shaped mandibular molars treated between 2018 and 2023 were analyzed. Canal morphology was classified by Fan’s system using cone-beam computed tomography (CBCT). Healing was evaluated radiographically at 12, 24, and 36 months using the Periapical Index (PAI). Associations between healing outcomes and variables—including canal type, pre-operative periapical lesion, and obturation quality—were assessed using the Chi-square test and logistic regression analysis. Significance was set at p < 0.05.

Results:
Overall success (complete + incomplete healing) was 88.9 %. C1-type canals exhibited the highest healing rate (94.3 %), significantly greater than C2 (78.6 %) and C3 (80.7 %) types (p = 0.019). Teeth without pre-operative lesions achieved 94.5 % success versus 76.8 % in those with lesions (p = 0.004). Adequate obturation was the strongest predictor of healing (OR = 5.71, p = 0.008), while pre-operative lesion presence reduced odds (OR = 0.35, p = 0.015). Mean PAI scores decreased from 3.74 ± 1.02 pre-treatment to 1.32 ± 0.64 at 36 months (p < 0.001).

Conclusion:
Endodontic treatment of mandibular molars with C-shaped canals can achieve high and stable long-term healing rates when managed with precise CBCT-based diagnosis, magnification, and thermoplastic obturation. Canal configuration, pre-operative pathology, and obturation quality are critical determinants of outcome, highlighting the importance of individualized and technically rigorous management of these complex anatomies.