Can we reinforce anchorage with mini-implants (tads) in aligner treatment?

It isn’t every day that you witness the emergence of technology so promising that it changes standard practices in orthodontics forever. With Temporary Anchorage Devices (TADs), we’ve been able to ascend to the next level of orthodontic treatment, especially with popular yet contentious systems like clear aligners.

TADs are not entirely new in the orthodontic literature. Orthodontists have been using them since the 1980s but their recent incorporation into aligner therapy has definitely turned some heads. Clear aligners are held in high regard over braces for their increased comfort, durability, hygiene, and of course, brilliant aesthetics. But what is typically the plus point for aligners – their inherent removability- is also what often works against them.

Since aligners are not “glued-on” to the tooth surfaces, unlike braces, the control and anchorage they provide can be lacking when dealing with complex orthodontic malalignments. Fixed appliance fanatics may very well recognize this issue, especially when compared with the continual force exerted by archwires on the teeth during braces treatment. Thus, it may be tricky for aligners to reproduce the same results as orthodontists are frequently looking for an anchor point from which to push or pull the teeth into a perfect alignment.

Why is anchorage important?

At the end of the day, the anchorage is the most important element in orthodontics. With proper anchorage, we can achieve the most stable place from which to apply skeletal and dental forces through orthodontic treatment.

Experts have compared shifting teeth positions in the jaw to moving a stick through the sand. When you move the stick through the sand, you will notice that the sand moves aside in front of the stick and instead fills up the space behind it. In the context of the oral environment, the “sand” forms the bone cells and the cells of the periodontal ligament, essentially tissues that attach the tooth to the bone. Upon the application of force on the teeth by aligners, these tissues slowly begin to move aside.

But for this to occur uniformly, the force will need a fixed point to push against. For example, if you’re floating free in the water, it will be difficult to move the stick. But, if you do the same action with your feet firmly planted into the sand, it becomes possible. In the same context, if the back teeth are used as anchors to move the front teeth, movement will be possible easier.

Throughout history, we have gone through a variety of anchorage devices, both extraoral and intraoral, such as cervical and hi-pull headgears, J-hook facebows, dental tip-back bends and inter-arch springs, and elastic or fixed propulsion devices. However, since most anchorage devices (including the ones mentioned above) require extensive patient compliance, the results of orthodontic treatment can be greatly compromised.

This is where we are introduced to a relatively new concept of anchorage – in the form of mini-implants called temporary anchorage devices.

What is a temporary anchorage device?

A temporary anchorage device (TAD) is a small, surgical-grade titanium screw (1.5 to 2 mm in diameter) that is attached to your jaw bone and is used in association with clear aligners or braces as an alternative to headgear. As their name suggests, these are temporarily fitted devices that are placed during some months of treatment and then subsequently removed when sufficient tooth movement is achieved.

What can TADs do?

TADs work best for complex orthodontic tooth movements when aligners alone cannot achieve the intended results. For example, in cases of intrusion of the upper and lower teeth, aligners may not be able to produce appropriate tooth movements because their “grip” on the teeth is comparatively weaker than for wire-and-bracket braces. Therefore, in such a case, buccal and lingual TADs can be placed and supported with the help of elastics in combination with aligners to stabilize the tooth movements.

They can be used to address more difficult cases, such as our-bicuspid extractions, orthognathic surgical cases, and Class II cases. Experts also believe that when used in conjunction with aligner therapy, TADs can significantly shorten the overall treatment length.

TADs are placed with a minor in-office procedure and are typically required only for a few months. However, the exact duration of placement will be determined by your orthodontist.