Cone-Beam Computed Tomographic Evaluation of Mandibular Lingual Canals and Foramina for Safe Implant Placement in Prosthodontics

Abstract

Background: The Mandibular Lingual Canals (MLCs) and Mandibular Lingual Foramina (MLFs) are important anatomical structures of the anterior mandible that transmit small neurovascular bundles. Their considerable variation in number, size, course and anatomical position may increase the risk of hemorrhagic and neurosensory complications during dental implant placement and other surgical procedures. Cone-Beam Computed Tomography (CBCT) provides three-dimensional visualization of these structures and allows detailed preoperative assessment. Objective: To evaluate the anatomical and morphometric characteristics of mandibular lingual canals and foramina in adults using CBCT and to determine their associations with sex and age. Materials and Methods: This retrospective cross-sectional study analyzed 72 CBCT scans of adults aged ≥18 years obtained from a private hospital in Sulaymaniyah, Iraq. The sample included 27 males and 45 females and was divided into two age groups: 18-49 years (n = 57) and ≥50 years (n = 15). The number of lingual canals, foramen diameter, canal length, canal direction and distances from the canal to the alveolar crest (L1), adjacent anterior tooth apex (L2), inferior mandibular border (L3) and Labial Cortical Plate (LC/CP) were assessed. Midline canals were classified as supraspinous, interspinous, or infraspinous. Statistical analyses were performed using independent-samples t-test, Mann-Whitney U test, chi-square test, or Fisher’s exact test, as appropriate. Results: Among the 72 patients, two lingual canals were most common (43, 59.7%), followed by one canal (21, 29.2%) and three canals (8, 11.1%). No significant differences were found in the number of canals according to sex (p = 0.998) or age group (p = 0.849). Males demonstrated a significantly greater mean canal diameter than females (1.27±0.38 mm vs. 1.08±0.30 mm; p = 0.018). No significant sex-related differences were observed for canal length, L1, L2, L3, or LC/CP. The mean L2 distance was significantly greater in participants aged ≥50 years than in those aged 18-49 years (11.99±5.32 mm vs. 9.78±3.05 mm; p = 0.039). A total of 131 canals were identified, with oblique canals being the most frequent (45.0%), followed by vertical (32.1%) and horizontal (22.9%) canals. Supraspinous and infraspinous positions each accounted for 40.5%, while interspinous canals accounted for 19.1%. Conclusion: Mandibular lingual canals and foramina demonstrate considerable anatomical and morphometric variation in the anterior mandible. Significant sex-related differences were observed in canal diameter, while age was significantly associated with the distance between the canal and the adjacent anterior tooth apex. CBCT assessment should therefore be considered an important component of preoperative planning for implant placement and other surgical procedures involving the anterior mandible to minimize the risk of neurovascular injury and hemorrhagic complications.