Mandibular skeletal changes induced by early functional treatment of Class III malocclusion: a superimposition study.

A superimposition study on mandibular stable structures was performed to evaluate changes in mandibular rotation and in the direction of condylar growth induced by early treatment of Class III malocclusion by a functional appliance (removable mandibular retractor). A sample of 18 children with treated Class III malocclusions, mean age at the first observation (immediately before the beginning of treatment) 5.47 +/- 1.14 years, mean age at the second observation 8 +/- 1.29 years, mean observation period 2.5 +/- 0.9 years, was compared with a control group of 18 children with untreated Class III malocclusions, mean age at the first observation 5.72 +/- 1.11 years, mean age at the second observation 7.86 +/- 1.44 years, mean observation period 2.27 +/- 0.92 years. No statistically significant difference between the two groups was recorded for positional (total) rotation of the mandible. A significant upward-forward direction of condylar growth was assessed in the treated group (p < 0.001). This therapeutically induced change in growth direction of the mandibular condyle was considered a skeletal sign of anterior morphogenetic rotation of the mandible, i.e., a mechanism compensating for excessive mandibular growth.