Abstract

Purpose: This study investigated the influence of alveolar bone morphology and density on mandibular canal (MC) visibility and mental foramen (MF) position in dentate versus edentulous posterior mandibles to enhance implant planning safety.

Materials and Methods: Archival CBCT scans from 148 adults (mean age 43.4 ± 16.2 years) were analyzed: 82 dentate and 66 edentulous cases. MC visibility at the first molar site was scored (0–3 scale) on panoramic and parasagittal views. Bone morphology was classified using a novel system integrating prior schemes (Types A–F), density per Lekholm and Zarb (D1–D4), and MF position measured relative to alveolar crest and inferior border. Statistical analyses included Chi-square, t-tests, and Kappa for reliability (P < 0.05).

Results: Edentulous mandibles showed significantly higher MC visibility on parasagittal views (53% completely visible vs. dentate; P < 0.05) and a trend on panoramic views (P = 0.051). Morphology distributions differed at MF (P = 0.032) and premolar (P = 0.037) sites, with posterior Types A/B (lingual concavity/inclination; 65.6% at molars) predominant and a novel Type D (narrow base, wide crest; 6–13%) identified. Edentulous cases exhibited denser bone (higher D1; P < 0.05). MC visibility associated with morphology in dentate (P < 0.05) and density in edentulous (P < 0.05) groups.

Conclusions: Edentulism enhances MC visibility via remodeling-induced density changes, with morphology-driven effects in dentate jaws. These findings underscore CBCT's role in mitigating inferior alveolar nerve injury risks, advocating population-specific classifications for precise posterior mandibular implant protocols.