Functional Appliances are a group of appliances that offer bite correction by changing the position of one arch in relation to the other. Sometimes these are fixed, most commonly they are a removable appliance.

There have been variations over the years in design but the principles have remained the same and well established in the literature.

The most common type addresses the situation where the upper front teeth protrude too far in front of the lower. Conventional functional appliances can only be used when the patient is still growing.

Usually, full braces require most of the adult teeth to be erupted. A functional appliance can be fitted prior to the eruption of all the adult teeth. If a large correction is required and it may be some time before the necessary teeth erupt, a functional appliance will achieve part of the correction while growth continues.

In most cases, a functional appliance will achieve a better bite but braces will still be required for the detailed correction of individual teeth and the final bite correction.

A functional appliance should be worn for about 9 months, depending on tooth eruption and the timing of the braces.