Stability of skeletal changes after activator treatment of patients with class III malocclusions

The aim of this study was to examine the skeletal changes produced by Class III activator during the treatment of patients with skeletal Class III malocclusions and to characterize the stability of these changes in the years after treatment. The samples consisted of 19 girls and 9 boys. Their mean age was 9.6 +/- 1.4 years at the beginning of the treatment. The average treatment time was 1 +/- 0.5 years. Measurements were obtained from cephalometric head films taken before treatment, at the end of treatment, and 6.6 +/- 2.1 years after the end of activator treatment. During the treatment, the Class III activator produced a statistically significant increase in the ANB angle, and this change remained through the postactivator period. The gonial angle exhibited a compensatory decline during the postactivator period. The skeletal profile was improved with treatment and was not lost during the posttreatment period despite significant increase in maxillomandibular differential. This study indicates that Class III activator may be a viable mode for the initial stage of skeletal Class III treatment, in conjunction with the period of postfunctional fixed or removable appliance therapy to improve the occlusion.