A Novel Imaging Technique for Analyzing Condylar Movement During Mastication in Patients With Jaw Deformities: Four-Dimensional Computed Tomography

Abstract

Objective: This study aimed to reveal characteristic condylar movements in patients with jaw deformities. Study Design: Thirty patients with jaw deformities before surgery were enrolled and instructed to chew a cookie during 4-dimensional computed tomography (4DCT). The distance between the most anterior and posterior positions of the bilateral condyles on 4DCT images was measured and compared among patients with different skeletal classes. Correlations between the condylar protrusion and cephalometric values were also determined. Results: The distances of condylar protrusion during mastication were significantly greater in the skeletal class II group than in the skeletal class III group (P=0.0002). Significant correlations were found between the distances of condylar protrusion during mastication and the sella-nasion–B point angle (r=−0.442, P=0.015), A point–nasion–B point angle (r=0.516, P=0.004), sella-nasion plane to ramus plane angle (r=0.464, P=0.01), sella-nasion plane to occlusal plane angle (r=0.367, P=0.047), and condylion–gonion length (r=−0.366, P=0.048). Conclusion: Motion analysis with 4DCT images revealed that condylar movement in patients with retrognathism was larger than in patients with mandibular prognathism. Skeletal structure was therefore correlated with condylar movement during mastication.