Temporary anchorage devices

The problem they solve

Every orthodontic force has an equal and opposite one. Pull a front tooth backward using the molars as the anchor, and the molars come forward. In many cases that loss of anchorage is acceptable. In others — closing a large extraction space, retracting protruding front teeth, intruding an over-erupted molar — it ruins the plan.

A TAD is anchored in bone rather than to other teeth, so it does not move. Force can be applied against it in one direction only, and the reaction is absorbed by the skeleton.

What placement involves

Local anaesthetic is used, the screw is placed through the gum into bone, and the whole procedure takes a few minutes per screw. Most patients report pressure rather than pain and take nothing stronger than ordinary pain relief afterwards. The site is tender for a day or two. The screw sits mostly flush, with a small head above the gum to attach a chain or spring.

The main aftercare is hygiene: keep the area clean with a soft brush and the rinse you are given, because inflamed tissue around the head is the usual reason a screw loosens. If one does loosen, it is removed and, if still needed, replaced at a different site.

What they make possible

• Closing extraction spaces without dragging the back teeth forward.
• Retracting front teeth further than conventional anchorage allows.
• Intruding teeth that have over-erupted into a gap, so a crown or implant can be placed properly.
• Correcting asymmetry where one side needs different mechanics from the other.
• Achieving in some adults what would otherwise require jaw surgery — though not in every case, and this is a discussion to have specifically rather than assume.

Removal

They are temporary by design. Once their job is finished they are unscrewed, usually without anaesthetic, in under a minute. The tissue closes over within days and nothing remains.