Anatomical variations in the interforaminal regions of candidates for implant-assisted overdentures: a cross-sectional CBCT analysis.

Implant-supported overdentures are becoming a common treatment modality, providing functional and esthetic results for patients in need of full-mouth rehabilitation. Because anatomical variations in the residual ridge affect treatment planning, the aim of this retrospective study was to present quantitative descriptions of the interforaminal region by evaluating a large series of cone beam computed tomographic (CBCT) images of the mandibles of edentulous patients in need of anterior dental implants. The sample included a total of 180 CBCT scans (360 sites) of patients requiring endosseous implant placement in the anterior region of the mandible for implant-assisted overdentures. The CBCT images were evaluated for parameters such as ridge height, width, angulation, and undercuts; crestal height; and corticocancellous bone ratios. The statistical analyses included the independent-samples t test and chi-square analysis. The mean (SD) ridge height was 18.16 (0.36) mm on the right side and 17.79 (0.38) mm on the left side and was significantly greater in men than in women (P = 0.02). Men also had a significantly greater cortical crest height than women (P = 0.01). The prevalence of ridge undercuts in the buccal cortex was 10.0% on the right side and 7.2% on the left side, and these undercuts had mean (SD) depths of 1.52 (0.62) mm and 1.48 (0.60) mm on the right and left sides, respectively. The ratio of cortical bone to cancellous bone was significantly greater in men than in women (P = 0.03). The mean (SD) ridge angle was 14.51 (6.54) degrees on the right side of the mandible and 13.05 (6.47) degrees on the left side, a statistically significant difference (P = 0.00). Moderate positive correlations were detected between the patient age and both the ridge widths (P = 0.00) and cancellous bone widths (P = 0.01). Moderate negative correlations were detected between the patient age and both ridge height and cortical crest height (P = 0.00). The widest ranges of variation belonged to ridge angle and ridge height, respectively, but the differentiation between the right and left sides was clinically insignificant. Knowledge of the patient's anatomical variations will allow the clinician to formulate an individualized treatment plan.