Maxillary and cranial base changes during treatment with functional appliances

Abstract The purpose of this prospective study was to investigate the maxillary and the cranial base changes after treatment with the Harvold activator and the Frankel function regulator appliances. Forty-two children, who are 10 to 13 years old, with Class II, Division 1 malocclusions were matched in triads according to age and sex and randomly assigned to either the control, Harvold activator, or Frankel function regulator group. Lateral cephalometric radiographs were taken at the start of the study and 18 months later. Both appliances reduced the overjet by tipping the maxillary incisors palatally and, as a consequence, the length of the maxillary arch was reduced. The appliances had no effect on either the horizontal or vertical position of the maxillary molars. Small, but statistically significant, changes in the cranial base angle in the Frankel function regulator group were attributed to relatively large changes at basion in several children, influencing the results because of the small size of the sample. The appliances had no effect on the position of the maxilla. (Am J Orthod Dentofac Orthop 1996;109:616-24.)