Effects of Rapid Maxillary Expansion on the the Human Craniofacial Skeleton

Abstract

We studied the effect on the craniofacial skeleton of rapid expansion of the maxillary arch using resistance wire strain gauges to measure the maxillary expansion forces on a dried human skull with mixed dentition. We found that the expansion created significant forces in the craniofacial skeleton, with the highest stresses being in the sutures.
      We also rapidly expanded the maxillary arch of 8 patients to investigate movement in the maxillary lateral segment, and carried out measurements on posteroanterior cephalograms, occlusal x-ray films, and dental casts. The expansion at the crowns of lateral teeth was greater than the screw expansion. The buccal tipping at the maxillary first molars was a maximum of 13.5°, a minimum of 0°, and averaged 4.57°for the 8 cases.
      We found that rapid maxillary expansion definitely caused midpalatal suture opening, although a portion of the expansion resulted from buccal tipping of the lateral segment.