Functional appliances are devices used to correct a significant disharmony in the relationship between the upper and lower jaws.  They work by influencing the growth and development of a growing patient.

The most common use of a functional appliance is to encourage the forward growth of a retrusive or “under-developed” lower jaw.  The functional appliance holds the lower jaw forward over a period until the teeth, jaws and joints have “adapted” and the desired jaw position has been obtained.

The effectiveness of a functional appliance depends on:

• how much the appliance is worn
• how quickly the patient is growing

Functional appliances align the jaws not the teeth, so they are usually used as a first stage of treatment (in a growing patient with a significant jaw disharmony) prior to the alignment of the teeth with fixed appliances (braces).

The most common types of functional appliance are listed below:

Fixed functional appliances:

• Forsus appliance (pictured)

http://solutions.3m.com/wps/portal/3M/en_WW/unitek-ww/home/products/intraoral/forsus/

Removable functional appliances:

Twin Block appliance