Nonsurgical rapid maxillary expansion in adults: Report on 47 cases using the Haas expander

Rapid maxillary expansion (RME) in the adult is thought to be an unreliable procedure with several adverse side effects and, consequently, surgically assisted RME is considered the preferred procedure. The purpose of this pap er is to study the efficacy of nonsurgical RME, and to determine the incide nce of complications such as relapse of the expansion, pain and tissue swel ling, tipping of the molars, opening rotation of the mandible and gingival recession. Rapid maxillary expansion using a Haas expander was examined in 47 adults and 47 children. A control group of 52 adult orthodontic patients who did not require RME was also studied. Students' t-test, and the analys is of variance followed by the Scheffe test were used to determine if there were significant differences among time periods and among the 3 study grou ps, The mean transarch width increase was similar in adults and children wh o had RME; 4.6 +/- 2.8 compared to 5.7 +/- 2.4 mm for the molars and 5.5 +/ - 2.4 compared to 5.7 +/- 2.5 mm for the second premolars, In the adults, t ransarch expansion and the correction of the posterior crossbites were stab le following discontinuance of retainers (mean 5.9 years). If the expander was properly fabricated, and turned no more than once a day, the procedure was well-tolerated. Rapid maxillary expansion in adults flared the molars b uccally only 3 degrees per side. The mandibular plane and lower facial heig ht were unchanged. The adults achieved 18% of their transmolar expansion at the height of the palate and the remainder with buccal displacement of the alveolus. The children achieved 56% of their expansion by an increase at t he height of the palate with the remainder due to displacement of the alveo lus. There was some buccal attachment loss (0.6 +/- 0.5 mm) seen in the fem ale subjects associated with RME, but the extent was clinically acceptable. This resulted in significantly longer clinical crowns, but rarely caused e xposure of buccal root cementum, Complications were infrequently observed o r of minimal consequence. The results indicate that nonsurgical RME in adul ts is a clinically successful and safe method for correcting transverse max illary arch deficiency.