Computed Tomographic Analysis of the Mandibular Body and Ramus in Japanese Patients: Relevance to Bone Harvesting From the Mandibular Ramus.

PURPOSE: The aims of this study were to use computed tomography (CT) imaging to determine the anatomical features of the mandibular body and ramus in Japanese subjects and to relate the findings to bone harvesting from the mandibular ramus. MATERIALS AND METHODS: The mandibles of 100 patients (28 males and 72 females) under dental implant treatment plan were observed on CT imaging (slice thickness, 0.625 mm). The linear distance between the superior aspect of the inferior alveolar nerve canal and the alveolar crest (distance A), the linear distance between the buccal aspect of the inferior alveolar nerve canal and the buccal cortical bone (distance B), the thickest width of the buccal cortical bone (distance C), and the thinnest width of the buccal cortical bone (distance D) were measured in the same coronal plane at 4 specific locations (section 1: the distal aspect of the first molar, section 2: the distal aspect of the second molar, section 3: the 10 mm distal aspect of the second molar, and section 4: the 15 mm distal aspect of the second molar). RESULTS: In the measurement of distance A, the minimum section among the male subjects was section 2 (12.55 ± 3.00 mm), whereas among the females, the minimum section was section 3 (11.82 ± 2.85 mm). In the distance B measurements, the maximum value was at section 2 (males: 6.36 ± 1.33 mm, females: 6.32 ± 1.39 mm) and the minimum value was at section 4 (males: 3.85 ± 1.74 mm, females: 4.75 ± 1.47 mm). Regarding the distance C measurements, the values of all subjects ranged from 3.10 to 4.41 mm, and the distance D values were approximately 2 mm. CONCLUSION: In Japanese patients, a rectangular piece of cortical bone up to 2 mm thickness may be harvested from the ramus, the length of the rectangular graft may approach 26 mm, and the height may be 10 mm for the safest harvesting from the mandibular ramus.