Functional Appliances

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functional appliances

Children in their early teens might sometimes need functional appliances when normal braces (also sometimes called train track braces) will only fix one part of the problem: teeth alignment. A functional appliance is also a type of brace, but it has another function: it corrects ‘class II’ problems – bite problems; where growth needs to be guided. Functional appliances can be either removable or fixed and are made of plastic.

Orthodontic functional appliances correct problems where the top teeth bite over the lower teeth. Your child’s orthodontist will, after assessment with you present, advise you on whether a removable functional appliance or a fixed one would be best for your child’s specific needs. By and large removable functional appliances consist of an upper and lower part which interlocks in a way that it effectively aligns the lower jaw better. The other functional appliance type consists of one piece only, but it is less popular because it has been found to not adapt to the teeth as well as the two-part option.

At Cronauer&Angelakis, we like to use 2 types of functional appliances:


Bionator is a class II functional appliance that aligns the profile of the patient and therefore enhances it by bringing the lower jaw forward. Your doctor might use it in a situation where your child’s lower jaw is not growing as fast as the upper jaw, with the result that it might look as if the child doesn’t have a chin.


An orthodontic retainer is used to keep your teeth in their new positions once you have graduated from your braces! Braces will have stretched the ligaments in your mouth and moved your teeth, and if you don’t wear a retainer afterwards, they will try to snap back to their original positions. Your retainer will keep your teeth nice and straight after your braces have been removed.

Rest assured though that your doctor will explain the purpose and use of these appliances thoroughly and without any rush to you, so that both you and your child will feel safe and comfortable that the whole process will go smoothly!