Evaluation of mandibular rotation after the effects of rapid expansion of the median palatine suture

Abstract

The studies concerning the rapid expansion of the median palatine suture, by using some appliances that expand the maxillary dental arch, show that the maxilla moves downward and forward, causing alterations in the occlusion, such as anterior bite opening and an increase of the angles of the occlusal and mandibular planes values. This study aimed at evaluating the alterations after the rapid maxillary expansion by using two types of expanders (Haas – GI and Hyrax – GII). The sample consisted of 93 lateral cephalometric radiographs from 31 Brazilian individuals (15 females and 16 males) between 9 and 16 years of age (mean age 13 years and 2 months). Radiographs were taken from each individual in the pre-expansion, immediately after expansion, and at the conclusion of the leveling stage. Angle measurements PP.GoMe, NBa. GoMe and NS.Gn showed a statistically significant increase in the pre-expansion and the leveling stages in both groups. The clockwise, downward and back rotational displacement of the mandible was verified by the statistically significant increase in the angle measurements studied in the postexpansion stage, remaining in the final leveling stage for both groups. Key words: Orthodontics. Palatal expansion technique. Orthodontics corrective.