Three-dimensional computerized tomographic orbital volume and aperture width evaluation: a study in patients treated with rapid maxillary expansion

ObjectiveThe purpose of this study was to assess the influence of rapid maxillary expansion (RME) on orbital volume and aperture width measurements by using freeware software with DICOM data from low-dose-protocol multidetector computerized tomography (MDCT).Study designThe subjects consisted of 30 patients (12 male, 18 females) treated with a Hyrax Palatal Expander, activated 3 times per day (0.25 mm per turn of the screw) for an average of 18 days. Low-dose MDCT was performed immediately before (T1) and after (T2) treatment. DICOM data was exported into the open-source OsiriX Medical Imaging software (www.osirix-viewer.com), the data reoriented to a standard projection, and then orbital volumetric and maximum aperture measurements performed.ResultsOrbital mean volumes increased significantly from 18.81 ± 1.23 cm3 (T1) to 19.53 ± 1.26 cm3 (T2). Orbital aperture width also increased significantly from 36.02 ± 1.24 mm (T1) to 37.11 ± 1.01 mm (T1).ConclusionsRME produces small but significant increases in orbital dimensions. However, RME does not produce drastic changes of the normal architecture of the orbital bones and is unlikely to alter the normal anatomy of the face.