Orthodontic mini-screws (TADs) — what are they and when are they used?

Orthodontic mini-screws (TADs) — what are they and when are they used?

Orthodontic mini-screws (referred to in the literature as TADs — Temporary Anchorage Devices) do not replace a tooth. They are not used for chewing. They serve no aesthetic function. They are small titanium screws — less than one centimetre in length — inserted into the bone of the maxilla or mandible for the duration of orthodontic treatment, as an anchorage point for the forces that move the teeth. After treatment they are removed.

This sounds unremarkable, but it is one of the most important tools to have appeared in orthodontics over the past two decades. It has made it possible to resolve cases that were previously eligible only for surgical treatment. It has delivered a precision that conventional biomechanics, relying solely on the patient's own teeth, could not provide. This article explains what TADs are, how they work, when they are used and what the patient has a right to expect. The tone is deliberately technical — because the subject requires it — but we endeavour to explain every concept that goes beyond the knowledge of an average patient.

What are TADs — definition and characteristics

Orthodontic mini-screws are small screws made of titanium or a titanium alloy, typically 1.2–2.0 mm in diameter and 6–12 mm in length. They are inserted into the cortical bone of the alveolar ridge (less commonly into the palate or the area of the mandibular ramus) between the roots of adjacent teeth or in non-dental areas. The procedure takes a few minutes, under local anaesthesia, similar to a simple surgical procedure. After orthodontic treatment is complete the mini-screw is unscrewed — equally quickly.

The key difference between TADs and a conventional dental implant: a dental implant is designed to integrate permanently with the bone (osseointegration). TADs are designed NOT to integrate permanently with the bone — their surface is smooth. This means they can be removed after a few months without difficulty.

During orthodontic treatment the mini-screw serves as a "fixed anchor". Elastic chains, springs or wires are attached to it, transmitting force to specific teeth — and those teeth move while the mini-screw itself remains stationary. This sounds straightforward, but it solves a fundamental problem in conventional orthodontics.

Why teeth themselves make a poor anchor — biomechanics in plain language

Newton's third law: every force has an equal and opposite reaction. In orthodontics this means that if we apply a force to tooth A (wanting to move it), the same force acts in the opposite direction on the teeth B to which tooth A is "connected" through the orthodontic appliance. If teeth B are stronger (e.g. more numerous or more massive), teeth A will move while B will stay put. If they are of similar mass — both will move towards each other.

This is the foundation of conventional orthodontic biomechanics. The orthodontist selects anchorage points so that the teeth to be moved have a point of resistance in other, stronger teeth. Often this works very well — but not always. In three classic situations conventional anchorage fails:

  • Retracting anterior teeth after premolar extractions — we want to retract only the incisors, but the posterior molars are pulled forward and an additional anchorage point would be helpful.
  • Open bite — we want to "push" the upper posterior teeth into the bone (intrusion), but conventional teeth do not provide a point of resistance acting vertically.
  • Distalisation of molars (moving them backward) — very difficult without additional anchorage, because there is nothing "behind them" that could push them.

In each of these situations TADs change the rules of the game. We insert the mini-screw into bone at the point where we need an immovable anchor — and the orthodontic force acts only where it is intended, without "side effects" in the form of movement of teeth that were supposed to stay in place.

Table: classic orthodontic challenges → how TADs solve them

Orthodontic challengeConventional approach (without TADs)Solution with TADs
Retraction of incisors after extractionsStabilising posterior teeth with a utility arch; risk of anterior drift of the molars (anchorage loss)TADs between the roots → pure incisor retraction without posterior tooth movement
Intrusion of posterior teeth in open biteLargely ineffective — often requires surgeryTADs placed high in the alveolar process → direct molar intrusion; a significant proportion of cases resolved without surgery
Molar distalisationExtraoral appliance (headgear) — now used less and less frequently; depends on patient complianceTADs as a permanent anchorage point → distalisation without a headgear, without compliance dependency
Closure of a large gap after molar extractionDifficult — often insufficiently effectiveTADs stabilise the plan and allow the gap to be closed predictably
Correction of significant asymmetry without surgeryOften impossible without surgeryIn selected cases TADs enable correction without an operation
Guided eruption of an impacted canine into the archConventional extrusion with tooth-borne anchorage — limited biomechanicsTADs as support for precise extrusion (see our article on impacted canines)

The insertion procedure — step by step

TAD insertion is one of the simplest surgical procedures in dentistry. It takes a few to several minutes, is performed under local anaesthesia (as for a standard filling) and most patients rate the comfort as comparable to a simple restoration.

1. Diagnostics and planning

Before insertion the orthodontist assesses: bone density at the planned site, the distance between the roots of adjacent teeth, the thickness of bone in the transverse direction. In most cases a standard panoramic radiograph is sufficient, but in complex cases (e.g. a palatal mini-screw) CBCT — a three-dimensional cone-beam scan — is used. It allows the exact course of adjacent roots and nerve canals to be visualised.

2. Local anaesthesia

Standard infiltration anaesthesia — the same as for a routine filling. The patient feels a brief sting; the anaesthesia then takes effect within 2–3 minutes.

3. Insertion of the mini-screw

The orthodontist uses a special manual screwdriver. In most locations there is no need for prior drilling of the bone — the mini-screw has a self-tapping shank and is inserted directly through the mucosa. This takes 30–60 seconds from the start of insertion. The patient feels gentle pressure but no pain.

4. Stability check and early loading

After insertion the orthodontist checks that the mini-screw is stable (measuring the torque during insertion). If stability is good, the orthodontic force (elastic chain, spring) can be attached to the mini-screw at the same appointment — i.e. immediately. There is no need to wait for integration, as with a dental implant.

5. Maintenance

The mini-screw remains in the bone for as long as the treatment stage requiring it lasts — usually 6–12 months, sometimes longer. The patient is virtually unaware of it. Hygiene around the mini-screw is straightforward — gentle brushing of the area with a soft toothbrush, plus periodic rinsing with chlorhexidine if the orthodontist recommends it.

6. Removal

Removal of a TAD takes less time than insertion — usually without anaesthesia, because the process is virtually painless. The orthodontist simply unscrews the screw. The small wound in the mucosa heals within a few days, and after 2–3 weeks no trace of the mini-screw remains.

Risks and limitations

TADs are safe, but like any procedure they are not free from complications. The most commonly described:

  • Failure (loosening and loss of the mini-screw) — reported in the literature in a significant proportion of patients (ten-odd per cent). In the event of failure the mini-screw is removed and, after a short healing period, a new one is inserted in a nearby location. This is not a dramatic complication — more of a logistical inconvenience. 
  • Soft-tissue inflammation around the mini-screw — usually responds to improved hygiene and a short course of chlorhexidine rinses.
  • Damage to an adjacent root during insertion — very rare, avoidable through careful planning and, if necessary, the use of a CBCT scan before insertion.
  • Fracture of the mini-screw — very rare, mainly involving the removal of a difficult case after a long period of loading.

Risk factors for failure assessed by the orthodontist before insertion: low bone density, smoking, inadequate oral hygiene, location in the posterior mandible (lower success rates than other sites).

What TADs have changed in my practice — a clinical perspective

In our practice at Modern Dental & Orthodontics, mini-screws have become a routine tool in three main groups of cases: adults with moderate to severe crowding undergoing extraction treatment, adolescents and adults with an open bite where molar intrusion is the treatment of choice, and patients after combined orthodontic-surgical planning (TADs as post-surgical anchorage for final occlusal detailing).

Importantly — TADs are not a "panacea". They do not replace good planning or an experienced orthodontist. The decision to use them arises from the analysis of a specific case and a specific biomechanical challenge — not from marketing or the pursuit of novelty. A mini-screw placed in the wrong location, at the wrong time, in the wrong case will not help anyone.

Summary

Orthodontic mini-screws are small titanium screws that serve as a fixed anchor for the duration of orthodontic treatment. They allow orthodontic forces to be directed precisely where they are needed, without "side effects" in the form of movement of teeth that were supposed to stay in place. Thanks to them, a proportion of cases that previously required orthognathic surgery or an extraoral appliance can now be resolved with pure biomechanics. The insertion procedure is short and comfortable — comparable to a simple filling. After treatment the mini-screw is unscrewed and disappears virtually without trace.

The key is good planning: the right indication, the right site, the right time to apply loading. TADs are not "modernity for modernity's sake" — they are a tool that serves a purpose. And like every tool, they work well when used by an experienced team, in a well-thought-through plan. 

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Sources

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