Three-dimensional analysis of condylar changes in surgical correction for open bite patients with skeletal class II and class III malocclusions

The aim of this study was to quantify three-dimensional condylar displacements as a result of two-jaw surgery for open bite correction in patients with skeletal class II and class III malocclusion. Pre-surgical (T1) and post-surgical (T2) cone beam computed tomography scans were taken for 16 patients with skeletal class II (mean age 22.3 +/- 9.47 years) and 14 patients with skeletal class III (mean age 25.6 +/- 6.27 years). T2 scans were registered to T1 scans at the cranial base. Translational and rotational condylar changes were calculated by x,y,z coordinates of corresponding landmarks. The directions and amounts of condylar displacement were assessed by intra- and inter-class Mann Whitney U-test or t-test. Class II patients presented significantly greater amounts of lateral (P = 0.002) and inferior (P = 0.038) translation than class III patients. The magnitudes of condylar translational displacements were small for both groups. Skeletal class III patients had predominantly medial (P = 0.024) and superior (P = 0.047) condylar translation. Skeletal class II patients presented greater condylar counterclockwise pitch (P = 0.007) than class HI patients. Two-jaw surgery for the correction of open bite led to different directions and amounts of condylar rotational displacement in patients with skeletal class II compared to class III malocclusion, with greater rotational than translational displacements.