A comparison of the correction mechanism of two functional appliances

Objectives: Fränkel appliance and Activator are two functional appliances usually used on growing patients with Class II, division 1 malocclusions. The Purpose of this study was to evaluate the effects of the two appliances on growing patients with the same malocclusions. Methods: The material consisted of pre- and post- treatment cephalograms of 20 Fränkel cases and 20 Activator cases and were compared by the methods of cephalometric evaluation from McNamara and 22 soft-tissue measurements. And then use the statistics of t test to analyze the figures.Results: Both the functional appliances were favorable to Class II, division 1 malocclusions,and they could make the mandibular advance and lengthen, increase the lower anterior facial height and finally correct the Class II malocclusions efficiently by modifying the soft-tissues of the chin and improving the patients' facial appearance. But since the two appliances acted with different mechanism, they differed from each other. Fränkel appliance could make the soft tissues of the chin and the upper lip more favorably than the latter because of its lip bumper, while the latter could control the position of lower incisors better and make the upper incisors backwards—decrease of the overjet. Because the Activator might make the mandibular rotate clockwise, care must be taken when it was used in high mandibular plane angle cases, while Fränkel appliance might be a good choice. Conclusions: In clinical practice, suitable functional appliances should be selected for different patients to correct different malocclusions to reach a satisfied result.