Objective: To investigate condylar symmetry and condyle fossa relationships in subjects with functional posterior crossbite comparing findings before and after rapid maxillary expansion (RME) treatment through low-dose computed tomography (CT). Materials and Methods: Twenty-six patients (14 girls and 12 boys, mean age 9.6 6 1.4 years) with functional posterior crossbite (FPXB) diagnosis underwent rapid palatal expansion with a Hyrax appliance. Patients' temporomandibular joints (TMJ) underwent multislice CT scans before rapid palatal expansion (T0) and after (T1). Joint spaces were compared with those of a control sample of 13 subjects (7 girls and 5 boys, mean age 11 6 0.6 years). Results: Anterior space (AS), superior space (SS), and posterior space (PS) joint space measurements at T0 between the FPXB side and contralateral side demonstrated no statistically significant differences. After RME treatment (T1), all three joint spaces increased on both the FPXB side and the non-crossbite side. However, differences were statistically significant only for the SS when comparing the two sides at T1. SS increased more than AS and PS in the non-crossbite condyle (0.28 mm) and FPXB condyle (0.37 mm), and PS increased only on the FPXB side (0.34 mm). Conclusions: There were no statistically significant differences in condyle position within the glenoid fossa between the FPXB and non-crossbite side before treatment. Increases in joint spaces were observed after treatment with RME on both sides. These changes were, however, of small amounts.

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.)

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