Crossbite in the Mixed Dentition

Posterior crossbite is a common maloclusion in children, with a worldwide prevalence of 8% and even higher than 11% in the European population. Unilateral posterior crossbites can, if left untreated, cause asymmetrical growth of facial structures. This condition is unlikely to self-correct and therefore early treatment is recommended to allow normal growth. Various orthodontic appliances can be used to correct a crossbite, such as removable expansion plates or fixed expanders, such as slow quad helix (QH) expanders or rapid maxillary expanders (RME).

QH has been considered the first choice in the treatment of unilateral crossbite and is traditionally attached to the first permanent molars.