Abstract
<title>Abstract</title> <p> <bold>Background</bold> The posterior molar canal (PMC) has been implicated as a potential source of bleeding during mandibular third molar surgery, yet its true incidence and anatomical characteristics remain controversial due to limitations of conventional imaging. This study aimed to evaluate the detection rates and morphological features of the PMC using four imaging modalities. <bold>Methods</bold> A total of 389 participants (766 mandibular sides) were enrolled and examined using cone‑beam computed tomography (CBCT), spiral CT, 3.0T magnetic resonance imaging (MRI), or contrast‑enhanced MRI. Detection rates were compared using Fisher–Freeman–Halton exact tests and binary logistic regression. <bold>Results</bold> The detection rate of the PMC increased significantly with improved soft‑tissue resolution: 32.37% for CBCT, 63.21% for spiral CT, 80.72% for contrast‑enhanced MRI, and 93.75% for 3.0T MRI (P < 0.001). High‑field MRI consistently revealed a three‑branch architecture comprising apical foramen, periodontal ligament, and retromolar branches. The main trunk of the PMC was observed even in patients with congenital absence of the mandibular third molar germ, indicating that the PMC is an inherent anatomical structure rather than a developmental variant. <bold>Conclusions</bold> The PMC is a consistent anatomical feature of the retromolar triangle that has been systematically underestimated by conventional CBCT. Reliance on CBCT alone may lead to underappreciation of surgical bleeding risks during third molar extraction when the canal runs adjacent to the surgical site. Preoperative recognition of this structure, particularly on high‑resolution MRI, is clinically relevant for anticipating and managing intraoperative bleeding. </p>