Teeth move as a response to light pressure from orthodontic hardware. The arch wire (the one that runs across the teeth) puts pressure on the teeth and brackets (the metal part on a single tooth), which creates pressure. Your dentist will occasionally change your child’s arch wires which continue to put pressure on their teeth.
Over time, this moves teeth into their proper position. What happens is that the braces help to stretch the Periodontal Membrane, which holds down the bottom part of the teeth. When this happens, it loosens the tooth and bone grows in to help support the tooth in its new home.
Depending on their needs and the stage of treatment they are on, your child may need to wear elastics, headgear, a positioner or retainer. All of these help to further place pressure to help the teeth move to its proper position.