The effects of maxillary protraction therapy with or without rapid palatal expansion: a prospective, randomized clinical trial.

INTRODUCTION: The purpose of this controlled randomized clinical trial was to quantify the effects of maxillary protraction with or without palatal expansion.

METHODS: Forty-six children aged 5 to 10 years were randomly assigned to 1 of 3 groups: (1) facemask with palatal expansion, (2) facemask without palatal expansion, and (3) observation for 12 months. Cephalometric analysis with traditional cephalometric measurements, an x-y coordinate system, and an occlusal-plane analysis were used.

RESULTS: Student t tests showed no significant differences (P < .05) between expansion and nonexpansion groups in any measured variable. Comparisons of treated and control subjects showed significant (P < .01) treatment effects beyond normal Class III growth. Analysis of x-y coordinate variables showed the following: 2 mm additional forward displacement of the maxillary complex with counterclockwise rotation, mandibular clockwise rotation, posterior movement of B-point by an average of 1.5 mm, and forward movement of the maxillary dentition of nearly 1 mm. Analysis of traditional cephalometric measures showed improvements in ANB angle of nearly 4 degrees and Wits appraisal of nearly 4 mm. The occlusal plane analysis showed an apical base change of 4 mm, 1.5 mm forward displacement of the maxillary complex, mandibular clockwise rotation of 2.5 mm, and forward maxillary molar movement of 1.9 mm.

CONCLUSIONS: The results of this continuing 5-year clinical trial indicate that early facemask therapy, with or without palatal expansion, is effective to correct skeletal Class III malocclusions.