Variations in bone quantity in the posterior mandible: a cross-sectional cone beam computed tomographic study

In this retrospective cross-sectional study, cone beam computed tomography (CBCT) was used to assess the bone quantity variations in the posterior mandible of edentulous patients. The crestal cortical bone thickness, buccal cortical bone thickness, lingual cortical bone thickness, ridge height, ridge width, ridge angle, lingual concavity depth, and cortical to cancellous bone surface area ratio were measured at 631 sites on 130 CBCT scans of edentulous patients. The patient sample comprised 87 men and 43 women with a mean (SD) age of 63.0 (11.8) years. One calibrated observer made all of the measurements. The intraobserver agreement was calculated, and the results of the measurements were analyzed with the independent t test and Pearson correlation test. The crestal, buccal, and lingual cortical bone thickness and ridge angle decreased significantly with age, while the ridge width increased significantly with age (P < 0.05). The buccal and lingual cortical bone thickness, ridge height, ridge angle, and lingual concavity depth were significantly greater in men (P < 0.05). The buccal cortical bone thickness, ridge width, ridge angle, and lingual concavity depth increased significantly from the anterior toward the posterior region relative to the mental foramen (P < 0.05). A ridge height of greater than 8.0 mm, a ridge width of greater than 6.0 mm, and a ridge angle of less than 15° were noted in 74%, 80%, and 80% of the sites, respectively (P < 0.05). The anatomical variations found in the mandibular posterior region of edentulous patients necessitate comprehensive CBCT assessment prior to implant placement in this area.