Immunohistochemical and CBCT-based examination of differences between deformed and normal human condylar processes

The condylar process is the most common site of mandibular fracture; however, the biomechanics of this site are not well understood. Vascular endothelial growth factor (VEGF) is a marker for vasculogenesis and the formation of bone. Alkaline phosphatase (ALP) is also a biochemical marker of bone formation. To better understand the biomechanics of the condylar process, we examined the structure of the heads and necks of human mandibles from 35 male cadavers aged 25 to 90 years (mean, 61.5 years) using cone-beam computed tomography (CBCT). In addition, we used immunohistochemistry to assess the expression of the vascular markers VEGF and CD31 as well as the bone formation marker ALP. Significant differences were observed in the thickness of the posterolateral region of the cortical bone in the head of the mandible (p < 0.05) as well as in the medial (p < 0.001) and posterior (p < 0.01) regions of the neck of the mandible. VEGF accumulated more in deformed heads than in heads with oval-shaped structures. ALP was found in numerous small cavities of cortical bone in oval-shaped heads. These differences may be related to dislocation caused by muscle tension or the occlusion of temporomandibular joint movement.