Morphological and cortical bone assessment of the edentulous posterior mandible using CBCT Implications for implant planning and mandibular cortical index evaluation.

BACKGROUND: This study aimed to investigate the relationship between posterior mandibular ridge morphology, cortical bone characteristics, and the Mandibular Cortical Index (MCI), and to assess their potential impact on the complexity of dental implant placement. Understanding these parameters is essential to optimize implant planning, minimize surgical complications, and improve clinical outcomes, particularly in regions where anatomical variations pose increased risks. METHODS: In this retrospective observational study, 100 cone-beam computed tomography (CBCT) scans of edentulous mandibles were analyzed in Turkish population. Each mandible was evaluated through 10 sagittal cross-Sect. (5 from each side), resulting in 1000 sections. The sample consisted of equal numbers of male and female patients aged between 32 and 79 years. Morphological parameters, including lingual concavity and convexity, bucco-lingual width, cortical bone thickness (buccal and lingual), alveolar crest height, and ridge morphology types, were evaluated in sagittal sections. Ridge shapes were categorized as saddle, kidney, pen shape, toucan beak, straight, hourglass, or basal. The MCI was classified as C1 (normal cortex), C2 (moderate erosion), or C3 (severe erosion) based on cortical integrity. Statistical analyses were conducted to determine the relationships between MCI, ridge morphology, and bone parameters. RESULTS: A statistically significant relationship was observed between MCI groups and ridge morphology types (p < 0.001). The C3 group exhibited significantly thinner lingual cortical bone (0.81 ± 0.22 mm), lower alveolar crest heights, and increased bucco-lingual width compared to the C1 group (1.29 ± 0.26 mm, p < 0.001), along with lower alveolar crest heights and increased bucco-lingual width (p < 0.05). Basal-shaped ridges showed the widest bucco-lingual dimensions but the lowest alveolar crest heights, suggesting advanced vertical bone loss. Conversely, straight and pen-shaped ridges demonstrated greater lingual cortical thickness. Lingual concavity was more pronounced in cases with lower MCI. CONCLUSION: CBCT-based evaluation of mandibular ridge morphology and cortical bone integrity, supported by appropriate statistical analyses (ANOVA, Chi-square, Kruskal-Wallis), offers clinically valuable insights for implant planning. Incorporating these assessments helps identify patients at greater risk for complications, guides the need for augmentation procedures, and supports safer and more predictable implant placement. These findings underscore the clinical relevance of ridge morphology and MCI in preoperative risk assessment, helping clinicians tailor implant planning strategies to anatomical variations and minimize complications.