Axial four-dimensional computed tomographic images to analyze crosswise differences in protrusive condylar movement in patients who underwent mandibulectomy and free flap reconstruction

Objective Few studies evaluate condylar movement following mandibular reconstruction. The main objective of this study was to show that axial four-dimensional computed tomography (4DCT) could visualize bilateral protrusive condylar movement directly. We used axial 4DCT images to assess condylar protrusion in patients who underwent mandibular reconstruction. Methods We enrolled seven healthy volunteers (median age 30 years, range 27–38 years) and seven patients (median age 65 years, range 52–80 years), who underwent mandibulectomy (segmental in five, hemi in one, marginal in one) and free flap reconstruction (using the fibula in six and the radial forearm in one). Six study subjects were instructed to masticate a cookie during the 4DCT scan (the seventh made chewing motions). The distance between the most anterior and posterior positions of the bilateral condyles on 4DCT (axial view) images was then measured and compared between controls and patients using the Mann–Whitney U-test. Results The crosswise difference in the distances of condylar protrusion was significantly greater in patients than in the controls. Conclusion Axial 4DCT images can visualize a bilateral condylar protrusive path. Axial 4DCT images for patients who have undergone mandibulectomy and reconstruction may be useful for evaluation of functional movement of condyles.