Objectives: The present study aimed to compare the treatment outcomes of a fixed-functional appliance (Twin-Force Bite Corrector - TFBC) and a conventional removable functional appliance (Activator) in the treatment of skeletal Class II malocclusions.
Methods: The TFBC and Activator Groups each included 10 young adults possessing a skeletal Class II malocclusion, and the treatment outcomes of both groups were quantified and compared, using lateral cephalometric radiographs, with an untreated skeletal Class II Control Group.
Results: A skeletal Class I relationship and a marked reduction in overjet were achieved in both treatment groups; however, the duration of treatment was significantly shorter in the TFBC Group (0.45 years) when compared with the Activator Group (1.37 years) (p < 0.001). Effective length and sagittal positioning of the mandible underwent significant changes in the TFBC and Activator Groups. Vertical facial dimensions increased in each group; however, these increases were significantly greater in the Activator Group when compared to the TFBC and Control Groups (p < 0.05). Dentoalveolar changes also contributed to the reduction in overjet.
Conclusions: Although both appliances succeeded in eliminating the Class II relationship and improving the overjet and overbite, the short treatment time in the TFBC Group raises questions regarding the long-term stability of the results.