Appliances mean devices. All apparatus utilized in orthodontic treatments are called with the same name. Appliances have many types.
Some appliances can be moved in and out of mouth; these are called “moveable appliances”. Springs and screws placed on these apply a force on teeth to be fixed. Some appliances sit on both upper and lower jaws; these monoblock devices help conduct orthopaedic treatments.
Some appliances consist of grooved brackets glued onto teeth and wires applied on these brackets; these are called “fixed appliances”.
Your orthodontist makes the final call in appliance selection. As a rule of thumb, most effective treatment in shortest possible time is prioritized. Additionally, child’s willingness for treatment, their cooperation, and economic conditions of the family also affect appliance selection.