How do expansion appliances function in orthodontic treatment?

Expansion appliances are specifically designed to create more space in the dental arch by exerting forces that widen it laterally. This is particularly useful in cases of dental crowding, crossbites, or to facilitate the alignment of teeth and jaws. When the appliance is activated, it applies pressure to the teeth and bone on either side of the arch, promoting an increase in width. The biological response to this force results in the remodeling of the bone, ultimately leading to an expanded arch shape.

The action of these appliances is crucial for correcting occlusal relationships and ensuring adequate space for teeth to properly erupt. In contrast, options discussing the vertical height, tightening of the arch, or closing gaps do not accurately represent the primary function of expansion appliances in orthodontic treatment.