Maxillary transversal deficiency is characterized by unilateral or bilateral posterior cross-bite, crammed and rotated teeth, and narrow palate, and its treatment is surgically assisted maxillary expansion for adult patients. This procedure affects not only bones, but also the teeth (especially the post of the expander device), nasal cavity and air space, lips and surrounding soft tissues. The aim of the present study was to evaluate dento-skeletal alterations of patients presenting atrophic maxilla who underwent surgically assisted maxillary expansion using cone beam computed tomography (CBCT). For this, 14 patients underwent CBCT before and after (15, 60 and 180 post-operative days) surgically assisted maxillary expansion by subtotal Le Fort I osteotomy, and the thickness of buccal and palatal cortical bones and the angulation of the long axis of the upper posterior teeth (1 M, 2 M, 1 PM and 2 PM) were measured. Data were statistically analyzed. Results showed changes in thickness of buccal and palatal cortical areas analyzed, which allowed us to conclude that EMCA, even though using surgical techniques, teeth can be translated by displacement and buccal inclination. Furthermore, it was concluded that when the shift occurred and buccal tooth inclination, these seem to have been accompanied by buccal cortical bone resorption and bone formation in the cortical palate.