A Tomography Cone Beam Computed (CBCT) Analysis of Mental Foramen Location, Prevalence of Anterior Loop and Extension of Anterior Loop in the Local Population of Lahore: A Cross-Sectional Study

Abstract

Background: The precise location of the mental foramen (MF) and the variability of the anterior loop (AL) of the inferior alveolar nerve is of greatest relevance in the placement of implants, endodontic surgery, and osteotomy of the mandible. Anatomical variations may predispose to neurovascular damage if they are not appreciated. Cone-beam computed tomography (CBCT) offers accurate visualization, but population-based information on local population is limited.

Objectives: To determine distribution of MF zones, prevalence and frequency of the AL, demographic relationships, and bilateral symmetry in a local Pakistani population through CBCT.

Methodology: This cross-sectional descriptive study analyzed 217 CBCT scans (age range: 16–60 years). MF positions were characterized as four zones (A–D). Presence of AL was recorded as absent, unilateral, or bilateral. Loop extension was measured at deepest loop curvature. Descriptive statistics yielded prevalence and morphometric information. Independent and paired t-tests, one-way ANOVA, chi-square tests, logistic regression, and McNemar–Bowker χ² tests were utilized, and p ≤ 0.05 was considered significant.

Results: On the right, MF was most frequently found in Zone B (42.4%) and Zone C (42.4%), while on the left, Zone B (45.2%) and Zone C (38.7%) prevailed. AL was absent in 76% of scans, unilateral in 22.1%, and bilateral in 1.8%. Mean loop extension was 3.05 ± 0.68 mm (right) and 3.12 ± 0.57 mm (left) with no side, gender, or age difference (p > 0.4). Logistic regression had limited predictability value, but MF Zone C was inversely correlated with presence of loop (OR = 0.29; p = 0.022). Highly significant side-to-side asymmetry of MF location was detected by cross-tabulation (χ² = 22.26; p = 0.001).

Conclusion: The MF in local population sample was most commonly located between or in relation to premolars and exhibited high left–right asymmetry. The AL was relatively uncommon, but when encountered measured ~3 mm, highlighting the significance of individualized CBCT evaluation prior to surgical intervention in the interforaminal region.

Keywords (MeSH): Mental Foramen; Mandible; Cone-Beam Computed Tomography; Inferior Alveolar Nerve; Dental Implants;