Cone-beam computerized tomography evaluation of the maxillary dentoskeletal complex after rapid palatal expansion

Introduction: Rapid palatal expansion (RPE) is routinely used to correct transverse deficiencies in the maxilla, but its effects on the dentoalveolus are uncertain. The purpose of this study was to compare measurements made on cone-beam computerized tomography scans between patients with RPE treatment and controls to determine transverse dimension increases and the amounts of alveolar and dental tipping. Methods: Twenty-five patients with posterior crossbite who required RPE treatment and 25 sex- and age-matched controls (no crossbite) were orthodontically treated and received cone-beam computerized tomography scans at the beginning and middle of treatment. Transverse widths and several angulations were measured, and matched paired t tests used. Results: RPE treatment produced a significant increase in all measured transverse dimensions. Analysis of posttreatment angulation changes in the RPE group showed that the alveolus substantially tipped buccally by nearly 5.6 degrees (measured from a horizontal reference, the base of the hard palate). The angulations of the dentition, however, remained constant before and after treatment (<1 degrees of change) in both groups. Conclusions: These data showed no statistically significant amount of relative dental tipping after RPE treatment but significant alveolar tipping compared with the controls. (Am J Orthod Dentofacial Orthop 2010;138:486-92)