A functional appliance is one which changes the posture of the lower jaw by holding it open (or) open and forward. These are fixed or removable applicances which use forces generated by stretching of muscles, fascia and/or periodontium to change skeletal or dental relationship.

These are mainly used during the developing stage of children if there are signs of abnormal dental and/or skeletal relationship. For example, In cases where there is an excessive development of upper jaw, or a relatively small lower jaw, the child would be having trapped lower lip between upper and lower teeth. The myofunctional appliance or a Twin Block appliance restricts the growth of upper jaw and stimulates the growth of lower jaw.

It can also be used in Cl III cases by restraining or redirecting the development of lower jaw.

Twin Block Myofunctional appliances

Twin Block Appliance is made up of two independent plates; one is for upper jaw and other is for lower jaw. This therapy is generally used for patients who are in active growth stage that is normally 9 to 15 year of age.

The basic appliance positions the lower jaw forward to encourage active growth of lower jaw in proportion to upper jaw. It improves the intercuspation of upper and lower teeth and more important improves the profile of patient.

This appliance is usually worn for 6-8 months before fixed orthodontic treatment is started.