This case report describes the treatment of a 12-years-old child with an Angle Class II subdivision malocclusion in addition to transverse maxillary insufficiency and unilateral maxillary crossbite and the use of Rapid Maxillary Expansion (RME) followed by a fixed appliance to address it. The treatment objective was to address the posterior and anterior crossbite and restore dentition and occlusion. This case was successfully treated with a single lingual sheath hyrax screw bonded expansion in Phase I, it resolved clinically substantial palatal expansion and improved the maxillary arch width, allowing for fixed appliance therapy in Phase II to be applied.
