What are Functional Appliances?
These are appliances or devices that are used to correct a group of bite problems called ‘Class II’ malocclusion. These problems arise when the top teeth bite in front of the lower teeth. Functional appliances can either be fixed or removable.
Malocclusion can be corrected in the following 3 planes of spaces by both the fixed and removable functional appliances:

• Anterior-Posterior: Class II and Class III appliances are used here.
• Vertical: The appliances used here helps correct open or deep bite.
• Transverse: The expansion of either the maxillary or the mandibular arch is done by these appliances.

Advantages
The Functional appliances have the following benefits:

• It will help eliminate abnormal perioral muscle function that interferes with muscle growth.
• There will be no side effects of mechanotherapy.
• The patient might not need to spend too much time on the dentist’s chair.
• They are easier to maintain oral hygiene.
• They can be worn at night.

Functional Appliances Types
The functional appliances are divided into 2 types:

Fixed Functional Appliances
Orthodontists usually handle the bonding of these appliances to the teeth. These appliances provide an accurate movement for the teeth. The Fixed Functional Appliances have the following categories:

• Distalization Appliances
• Class II Appliances
• Class III Appliances
• Intrusion Appliances
• Mesialization Appliances
• Vertical Dimension Appliances

Removable Functional Appliances
Removable functional appliances are usually more popular among patients. They are made from separate upper and lower parts. These when interlocked place the lower jaw in a more advanced position. These appliances need not be bonded on the teeth and can be removed by the patient. The components are usually connected by an acrylic component called the Baseplate.  There are basically two types of components:

Passive Components
Majority of these appliances include components like Labial Bow and Adams Clasp, which are passive in nature.

• Labial Bow: This wire is attached to the baseplate going around the incisor teeth providing their retention. They have U-Loops at the end to activate it more.
• Adam Clasps: These are used for the retention of these removable appliances. They are usually fabricated in the molar areas. You can remove this clasp by holding the bridge of this clasp.

Active Components
These include the springs that provide the light force on the tooth to move it orthodontically. Screws and elastics are the other active components. A spring made of 0.5mm thick stainless wire is required to move one tooth, while, the thickness of the wires has to be either 0.6mm or 0.7mm to move more teeth or for a large multi-rooted tooth.

Treatment Principles
The orthodontist might use the following treatment principles:

Force Application:
The force that is applied on the tooth would be a compressive stress and strain. This can result in a primary alteration. This could be in form with a secondary functional adaptation.

Force Elimination:
Any abnormal and restrictive environmental influences on the dentition are eliminated using this principle leading to an optimum development. Skeletal and Dentoalveolar changes are produced by these components by acting on the following:

• Cruption
• Linguofacial Muscle Balance
• Mandibular Repositioning
  
  

Authored by DR.NIRANJAN P