Segment tilting associated with surgically assisted rapid maxillary expansion.

This study aimed to evaluate, via computed tomography, the direction and magnitude of the segmental tilting that may occur after surgically assisted rapid maxillary expansion (SARME) in patients with a transverse maxillary deficiency. Thirty adult patients with a transverse maxillary deficiency greater than 5mm were treated by SARME. The procedures consisted of bilateral zygomatic buttress and midpalatal osteotomies combined with the use of a tooth-borne orthopaedic device postoperatively. Axial and coronal images were obtained before and 6 months after SARME to evaluate the segment tilting. The greatest expansion occurred in the most inferior (5.4 +/- 1.1 mm) and anterior (4.0 +/- 1.3 mm) regions of the maxilla. The expanded segment tilted outward inferiorly and anteriorly in coronal and axial images, respectively. The segment tilting was 2.0 mm (2.3%) inferiorly and 3.1mm (12.8%) anteriorly. It can be concluded that an outward tilting occurs in the most inferior and anterior portions of the maxilla during SARME procedures. Hence the direction and magnitude of such segmental tilting must be considered preoperatively when determining the surgical objectives.