TAD, Temporary Anchorage Device
Orthodontic movement of a tooth includes three components: the active tooth, the tooth we want to move; the force module, which could be a combination of a spring, a wire, or elastic; and an anchor for the opposite end of the force. TADs or temporary anchorage devices deal with the third component.
The American Association of Orthodontists (AAO) defines anchorage as “Resistance to activation force. Anchorage may come from any of the following sources: intraoral-teeth; bone and soft tissue; extraoral-cervical, occipital, cranial.” Extraoral anchorage refers to different types of headgear.
Of the anchorage catagories listed by the AAO, teeth are the most commonly used anchor. While teeth are convenient anchors, they present significant limitations when used as anchors. The major limitations are:
- Stability – when a tooth is used as the anchor, the anchor tooth moves as well. Anchor tooth movement is usually undesirable.
- Vector or position – when a tooth is used as an anchor, force application is limited by the healthy positions of teeth.
The American Association of Orthodontists lists anchorage to bone in the definition; however, until recently anchorage to bone was seldom used due to complexity and expense. The recent advances in design and production of Temporary Anchorage Devices (TADs) virtually eliminated the previous obstacles.
A TAD is a device fixed to bone specifically for the purpose of providing orthodontic anchorage and is removed at the completion of treatment.
TADs can:
- Stabilize a tooth being used as an anchor
- Eliminate the need to use a tooth as an anchor
- Provide an anchorage point where tooth anchorage is not normally available
Orthodontics with TADs can:
- Reduce orthodontic treatment time by one third
- Eliminate the need for a headgear
- Provide a more ideal finish
- Allow limited tooth movement in preparation for a bridge, crown or implant without braces
- Close most open bites without surgery
- Eliminate the need for rubber bands
Dr. Nelson was one of the first orthodontists in the Austin area to use TADs extensively. Unlike most orthodontists Dr. Nelson places the TADs himself and does not refer his patients to other specialists for the procedure.
A TAD is an implant that is fixed to bone for the purpose of providing an absolute anchorage point for movement of teeth. It should also be pointed out that because it is considered to be a temporary anchorage device, it is removed and discarded after orthodontic treatment.
To move a tooth or group of teeth, a force is applied to the tooth or teeth as determined in the treatment plan. But while force actually moves teeth, for a force to work it must be attached to the teeth that are planned for movement and an opposing anchorage unit. The opposing anchor unit is usually other teeth, which also move or appliances like a headgear. We all know the problem with a headgear is getting someone to wear it enough. But the problem of movement of both ends of the force when teeth are used as the opposing anchor is equally limiting.
A TAD provides an immobile anchor at one end of the force, thus we are able to exercise a greater degree of control over tooth movement. (Absolute anchorage)
A TAD is capable of:
- Replacing a headgear
- Closing an open bite
- Opening a deep bite
- Correcting a Class II
- Correcting a Class III
- Correcting an occlusion asymmetry
- Uprighting a tipped molar in preparation for restorative without full braces
- Intruding or extruding teeth for restorative procedures usually without full braces
- Correcting a single tooth crossbite without full braces
- OGS can be simplified to one jaw
- TADs are good fixation points to manage post-OGS patients
A TAD (temporary anchorage device) is an implant that is temporarily fixed to bone for the purpose of supporting the teeth of the reactive unit or by eliminating the need for the reactive unit altogether. A TAD can be fixed to bone either mechanically (cortically stabilized) or biochemecially (osseointegrated).
It should also be pointed out that to be considered a temporary anchorage device, TADs are removed and discarded after orthodontic treatment
A TAD (temporary anchorage device) is an implant that is temporarily fixed to bone for the purpose of providing an absolute anchorage point for movement of teeth.
Prior to TADs, orthodontics primarly relied on reciprocal anchorage.
The importance of TAD to orthodontics is based on the fact that most tooth movement depends on reciprocal anchorage
While there are numerous methods to apply a force to teeth, each application of force is anchored by an active and reactive unit. The active unit is made up of the teeth the treatment is designed to move; the reactive unit is the opposite end of the applied force. In instances where the active and reactive units are teeth, both the units of teeth move (reciprocal anchorage), and when both units of teeth move, ideal tooth position is often not possible.
