Effects of a bonded rapid maxillary expansion appliance during orthodontictreatment

The aim of this prospective study was to evaluate changes in the transverse plane following use of an acrylic bonded rapid maxillary expansion (RME) a ppliance in growing individuals during the active phase of treatment. The s ample comprised 14 consecutively treated orthodontic patients (11 girls, 3 boys) who required the use of an RME device on the basis of their individua l treatment plans. The mean patient age at the start of treatment was 12.8 years, and the mean overall treatment time was 3.08 years. Seven posteroant erior cephalometric and two dental cast measurements were assessed. Repeate d measure analysis of variance and Duncan's multiple range test were used t o assess treatment changes. Lower nasal and maxillary base widths and angle s, and upper intermolar width increased significantly during RME treatment. Upper intermolar and intercanine widths measured from the dental casts als o increased significantly. Except for upper intercanine width, all measurem ents remained constant at the end of orthodontic treatment. The results of this study suggest that dentoskeletal changes in the transverse dimension f ollowing the use of an acrylic bonded RME are maintained satisfactorily at the end of fixed appliance therapy.