Differences of the condyle relocation range between skeletal class II and skeletal class III patients: a preliminary study

The present study aimed to preliminarily compare the differences of the condyle relocation range (CRR) between skeletal class II and skeletal class III patients. Twenty skeletal class II and twenty skeletal class III young adult patients underwent wide-field cone beam computed tomography (CBCT) scans of the maximum intercuspation position (MIP) and most comfortable forward relocation (MCFR). We superimposed the CBCT images in two positions according to the bilateral zygomatic bone surface structure and then measured the dental and skeletal CRRs in three-dimensional space. The median (interquartile range) dental and skeletal CRRs of skeletal class II malocclusion patients were 8.71 (3.55) mm and 8.47 (4.19) mm, respectively. The median (interquartile range) dental and skeletal CRRs for skeletal class III malocclusion patients were 1.37 (3.43) mm and 1.04 (1.44) mm, respectively. Both the dental and skeletal CRRs of skeletal class II patients were significantly greater than those of skeletal class III patients (p < 0.01). The CRRs of the different skeletal types exhibit obvious differences. Therefore, the range of physiological mandible positions in patients should be given attention during orthodontic diagnosis and treatment.