CBCT-based Morphological Assessment of the Mandibular Premolar and Molar Regions for Immediate Implant Placement in Vietnamese Adults: A Preliminary Study

Introduction / Background Immediate implant placement in the posterior mandible requires precise assessment of alveolar bone morphology due to proximity to the Inferior Alveolar Nerve (IAN) and variable cortical anatomy. Population-specific morphometric data for Vietnamese adults remain limited. Materials and Methods This preliminary cross-sectional study retrospectively analyzed 42 Cone-Beam Computed Tomography (CBCT) scans of Vietnamese adults. Virtual Straumann® implants were simulated at mandibular premolar and molar sites. Measurements included implant length, distance to the IAN, buccolingual and proximal bone thickness, mandibular cross-sectional morphology (Chan classification), and interradicular relationship (Chen classification). Statistical analyses were performed using t-tests, Mann–Whitney U tests, and one-way ANOVA. Results Mean implant lengths ranged from 15.07 ± 1.28 to 15.93 ± 1.68 mm. The second molar demonstrated the shortest mean distance to the IAN (0.06 ± 2.13 mm), with simulated canal encroachment in 23.8% of cases. Buccal bone thickness increased apically in molars, while lingual bone showed site-specific thinning. U-type mandibular morphology predominated (40–48%), and the septal interradicular relationship was most frequent (56–64%). Discussion Compared with Western populations, Vietnamese adults exhibited reduced IAN clearance and a higher prevalence of U-type mandibular morphology, resembling patterns reported in East Asian cohorts. These anatomical features explain the increased risk of neurovascular injury and cortical perforation during immediate implant placement in posterior mandibular sites. Conclusion Vietnamese adults exhibit population-specific mandibular morphology characterized by limited IAN clearance and frequent U-shaped cross-sections in the posterior regions. CBCT-guided virtual planning is essential for optimizing implant positioning and ensuring surgical safety.