Early post-treatment changes of circumaxillary sutures in young patients treated with rapid maxillary expansion

Objective: To test the null hypothesis that circumaxillary sutures do not show bony displacement in response to rapid maxillary expansion (RME) therapy. Materials and Methods: Subjects consisted of eight growing patients (two male and six female) with Angle Class I malocclusion, bilateral posterior crossbite, transverse maxillary deficiency, deep palatal vault, and dental crowding at the start of the treatment. A Hyrax palatal expander was used for each patient, and activation protocol required the screw to be turned three times per day (0.25 mm per turn) for an average of 18 days for all subjects. Multislice computed tomography (CT) scans were performed before rapid palatal expansion (time T0) and again at the end of the active expansion phase (time T1) without removing the expander. Measurements were carried out directly on the CT image using the OsiriX Imaging software program. Data were analyzed statistically by using the Wilcoxon signed rank test. Results: All linear measurements showed an increase between T0 and T1 and RME determined a widening of suture; however, sutures far from the maxilla showed a smaller degree of disarticulation. Conclusions: The hypothesis is rejected. Early treatment with RME produced a significant bony displacement by circumaxillary suture opening. The amount of changes of sutures depends on different factors relating to the subjects and varies between different sutures, showing that sutures that articulate directly with the maxilla face a greater influence by the RME compared with those located further away. (Angle Orthod. 2011;81:36-41.)