CBCT-Based Anatomical Assessment of Lingual Bone Availability Relevant to the Mental Foramen Bypass Concept in Posterior Atrophied Mandibles

Background/Objectives: Severe posterior mandibular atrophy presents anatomical challenges for implant rehabilitation because of reduced residual bone volume and the close relationship between the mental foramen, its anatomical variations, and the surrounding alveolar bone. Among these variations, the anterior loop may further influence the available lingual bone adjacent to the mental foramen. Despite the clinical importance of this region, quantitative three-dimensional anatomical information regarding lingual bone availability remains limited. Therefore, the aim of this retrospective cone-beam computed tomography (CBCT)-based study was to quantitatively evaluate the availability of lingual bone adjacent to the mental foramen in posterior atrophied mandibles and to assess the influence of the anterior loop on these anatomical dimensions, thereby providing quantitative anatomical information about this region. Methods: In a retrospective CBCT-based anatomical study, 110 CBCT scans of adult patients with atrophied mandibles were analyzed using standardized cross-sectional views perpendicular to the dental arch; linear measurements were obtained from the lingual cortical plate to the mesial (Point A), middle (Point B), and distal (Point C) borders of the mental foramen. The presence of the anterior loop was recorded. Descriptive statistics and independent-samples t-tests were performed to compare measurements between loop and no-loop groups (α = 0.05). Results: The mean measurements of the lingual bone were 7.22 ± 1.65 mm at Point A, 6.18 ± 1.55 mm at Point B, and 4.82 ± 1.38 mm at Point C, showing a gradual decrease from mesial to distal. An anterior loop was found in 26.4% of the cases. Significantly thinner dimensions of the lingual bone were observed with an anterior loop at all three measurement points (p < 0.01). Conclusions: The present CBCT-based anatomical study measured the amount of lingual bone available adjacent to the mental foramen in posterior atrophied mandibles and observed a significant correlation between the presence of an anterior loop and reduced lingual bone dimensions. These findings add to the knowledge of the anatomy of this area and could serve as the basis for future clinical studies to investigate the potential for a mental foramen bypass concept.