Class II treatment effects of the Frankel appliance

The objective of this work was to evaluate prospectively and cephalometrically the effects of the function regulator (FR) on dentoskeletal components during a treatment period of 28 months. The subjects consisted of 18 patients presenting with a Class II division 1 malocclusion, with a mean chronological age of 9 years 3 months at the beginning of treatment. The treated group was compared with a compatible control group of 23 untreated subjects observed during the same time period. Lateral cephalometric head films were obtained for the treated group at the beginning and after 28 months of treatment. The subjects in the control group belonged to a serial growth study sample from the Orthodontic Department at Bauru Dental School, University of Sao Paulo, for whom cephalometric head films were obtained annually from 4 to 18 years of age. The data for the control group were calculated from these head films. A student's t-test was used to compare the changes observed in the treated group with those in the control group. Differences were considered statistically significant at P < 0.05. The results demonstrated that the FR produced a statistically significant increase in the mandibular body, in the proportional size of the mandible to the maxilla and in lower anterior face height (LAFH); induced greater vertical development of the mandibular molars; reduced the overjet and overbite and produced an improvement in the molar relationship. Retrusion and palatal tipping of the maxillary incisors was also observed. However, the appliance did not produce any changes in maxillary development, in the growth pattern, or any improvement in the basal relationship. Therefore it was concluded that the effects of the FR in the correction of Class II malocclusions are primarily dento-alveolar, with a smaller participation of skeletal changes.