2 × 4 appliance in the mixed dentition stage: a scoping review of the evidence.

A great emphasis is currently given to the early correction of malocclusions to prevent further complications if left untreated. Interceptive orthodontics not only simplifies but also eliminates the need for later procedures. The 2 × 4 appliance is an orthodontic treatment modality applied during the mixed dentition period, particularly for malpositioned permanent upper incisors.