Maxillary sagittal and vertical displacement induced by surgically assisted rapid palatal expansion.

The purpose of this study was to investigate the sagittal and vertical effects on the maxilla induced by surgically assisted rapid palatal expansion. Twenty patients (average age, 25.6 years) who required a surgically assisted rapid palatal expansion procedure were available for this study. Each patient was banded with a Haas-type palatal expander, maxillary surgery was performed, and the expander was activated. Presurgical and postexpansion lateral cephalograms were taken for each patient. The measurements of SNA, Frankfort horizontal-nasion-A point, sella-nasion-palatal plane, A-point-nasion-perpendicular (in millimeters), 1-nasion-A-point, 1-sella-nasion, 1-nasion-perpendicular (in millimeters) were made on each cephalogram, and the presurgical and postexpansion tracings were superimposed on the cranial base to determine the changes in the anterior nasal spine and posterior nasal spine positions. Results showed that from the presurgical cephalogram to the postexpansion cephalogram SNA, Frankfort horizontal-nasion-A point and A-point-nasion-perpendicular had a mean increase of 0.60 degrees (P <.05), 0.65 degrees (P <.05), and 0.55 mm (P <.05), respectively; 1-nasion-A-point decreased 2.18 degrees (P <.05) and 1-sella-nasion decreased 1.53 degrees (P <.05). No significant maxillary vertical displacement was noted from the first cephalogram to the second. In conclusion, surgically assisted RPE did not significantly affect the maxilla vertically; however, it did induce a slight forward movement of the maxilla and a slight retroclination of the maxillary incisors sagittally (P <.05).