A tongue blade is commonly used in the early correction of incisor cross-bite, especially in children. It works by applying gentle pressure on the lingual surface of the lower incisors or labial surface of the upper incisors, guiding them into the proper position. This simple appliance leverages the natural forces generated by the tongue to help move the teeth without the need for complex orthodontic devices. It is most effective when the cross-bite involves only the incisors and when used during the mixed dentition phase. The tongue blade is not suitable for correcting posterior cross-bites, open bites, or deep bites as these conditions require different interventions.

Reference: Graber's Orthodontics, 7th Edition.