Radiomorphometric Assessment of the Mandibular Ramus and Symphysis as Intraoral Donor Sites for Autogenous Block Grafts: A Cone-Beam CT Study

Background The mandibular symphysis and ramus are frequently chosen intraoral donor sites for harvesting autogenous block grafts to augment deficient implant sites. Reliable grafting requires preoperative assessment of cortical thickness and cancellous bone density. This study compared cortical thickness and cancellous density of the ramus and symphysis on cone-beam computed tomography (CBCT) scans to guide safe and efficient block-graft harvesting. Methods Seventy archived CBCT volumes (42 females, 28 males; mean age = 60.3 ± 13.74 years) were analysed using Romexis® software. Ramus measurements were taken at the buccal shelf and ascending ramus 2 mm above the inferior alveolar canal; symphyseal measurements were made 5 mm mesial to the mental foramen, between the two mental foramina. Cortical thickness (mm) and cancellous density (Hounsfield units, HU) were recorded. Data were compared between sites and sexes with paired and independent t-tests (SPSS v21, α = 0.05). Results Mean cortical thickness was 1.49 mm in the ramus and 1.45 mm in the symphysis. Mean cancellous density reached 375 HU in the ramus and 902 HU in the symphysis (P < 0.001). Both parameters were significantly greater in males than females. Cortical thickness and cancellous density showed strong positive correlations between the two regions (P < 0.001). Conclusions Within the limitations of this study, the symphysis offers thicker cortical bone and markedly higher cancellous density than the ramus, suggesting superior primary stability for block grafts harvested from symphysis. These findings can refine pre-surgical planning and risk assessment for intraoral bone-block harvesting.