Asymmetric hybrid hyrax appliance for one-sided expansion of the maxilla

Visible cross-bite combined with forced bite is one of the main indications for orthodontic treatment. Narrowing of the maxilla in adult patients is often an indication to perform surgically assisted rapid palatal expansion (SARPE). The use of skeletal anchorage within the palate in the form of orthodontic mini-implants and Hyrax screw in some cases allows avoiding this procedure, and can also be successfully used in the treatment of adult patients. The aim of the study is to present an appliance for asymmetric expansion of the maxilla with palatal skeletal anchorage. The design of the appliance included skeletal anchorage in the form of two BENEfit-System orthodontic mini-implants (2 mm x 9 mm, PSM Medical Solution, Tuttlingen, Germany), BENEplate elements, orthodontic bands and Hyrax screw. The appliance was used in a patient aged 22 years and 7 months who had been diagnosed with one-sided lateral cross-bite on the premolars. The correction of malocclusion was hampered by the absence of the first and second molar on this side. After inserting the appliance into the mouth, the patient activated it once a day. Ten days later, the cross-bite was corrected. The skeletal anchorage of the device allowed eliminating forces applied to the teeth on the opposite side, resulting in one-sided expansion and the elimination of unilateral cross-bite.