October 01, 2018

Are TADs cost effective? A new trial

The introduction of temporary anchorage devices has revolutionised orthodontic treatment. But, are they cost effective? This new trial gives us an answer.

Temporary anchorage devices are a great method of reinforcing anchorage. Recent systematic reviews have shown that they are effective and safe. The data in this review was based on the effectiveness of TADs. However, in order to complete the picture on this innovation we need to consider cost-effectiveness. This has been nicely addressed in this new paper.


Niels Ganzer et al

European Journal of Orthodontics, 2018, 1–8 doi:10.1093/ejo/cjy041


A team from Sweden did this study the EJO published it.

In their literature review they described the use of miniscrews for anchorage reinforcement. They also discussed the concept of molar block anchorage. This is when the operator prepares anchorage based on the size of the roots of the teeth. For molar block anchorage they tie the second molar, first molar and second premolar together with ligatures to provide an anchor unit to retract a first premolar.

They set out to answer the following main question;

“Will the use of miniscrews as anchorage reinforcement reduce treatment costs when compared to molar blocks”?

What did they do?

They did a randomised controlled trial with a 1:1 allocation. The PICO was

Participants: 11-19 year old orthodontic patients requiring fixed appliance treatment and extraction of maxillary first or second premolar teeth.  They were also moderate to high anchorage cases with at least 75% of the extraction space required for en masse retraction.

Intervention: Temporary anchorage device (miniscrews)

Control: Molar block anchorage preparation.

Outcome: Anchorage loss and cost.

They collected data at the start of treatment at the end of the need for anchorage reinforcement.

They also measured tooth movement from 3D scans.

Finally, they calculated the direct cost of the treatment from the material costs of the appliances and the surgery time and the indirect costs from loss of income and transport costs.

What did they find?

They did not provide much information on the amount of anchorage loss in this paper. Nevertheless, they stated that this manuscript was in preparation. They found that the mean loss of anchorage for the miniscrews patients was 1.5mm and 2.8mm for the molar blocks. This is similar to other studies.

When they looked at the costs.  The median cost of the miniscrew treatment €4,680 compared to €3609 for the molar blocks. This was a difference of €829.00 and was statistically significant. Importantly, they attributed this to an increased number of attendance and treatment duration for the mini screw group. This was due to a longer finishing time of 5.1 months.  They suggested that this was a result of a longer period of mesial movement of the molars after the canines had been retracted.

Finally, they suggested that in cases requiring moderate need for anchorage reinforcement, the use of miniscrews was not cost-effective. However, miniscrews should be used for cases requiring maximum anchorage.

What did I think?

I thought that this was a well done randomised trial. However, it would have been helpful to interpret this data if the paper that outlined the effects of treatment had been published. This is still awaiting publication.  I found another paper on this trail in which the investigators reported pain and discomfort. The Angle Orthodontist published this paper. This revealed that the randomisation and concealment were good.

The findings in the current paper were very clinically relevant. The differences in cost were clinically significant. I thought that it was interesting that they felt these had occurred because of the need for forward space closure in the mini screw group.  This may represent “incorrect” use of mechanics with a new technique and I wonder if this would not happen now as we are more experienced in anchorage management with TADs?

As usual with clinical papers, it is up to you to interpret the findings. This interesting new paper does provide us with clinically relevant information to give to our patients.  I think that we should look forward to all the papers on this trial being published. This is a good paper to discuss in the comments section of this blog. But can we please avoid an extraction/non extraction breathing, profile and other magical stuff discussion?

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Have your say!

  1. Interesting to read that absolute anchourage with a TAD is not absolute. There was a 1.5mm loss of anchorage in this study. That can be a significant amount of space when it occurs bilaterally.

    • Dear Richard Rapoport,

      Thank you for your comments. I understand that this article can only be understood when it is read in the context of the “manuscript in preparation”. This manuscript has now been published in the current issue of the American Journal of Orthodontics & Dentofacial Orthopedics:

      It is important to understand that the used miniscrew concept was direct anchorage. The miniscrews were inserted and immediately loaded when space closure started. As we highlight in the AJODO article occurs the majority of the 1.5 mm anchorage loss during leveling & alignment (i.e. before the miniscrews are inserted). During space closure, the mean anchorage loss was 0.2 mm.

  2. Costs cannot be compared across countries not even or especially within the EU. Cost of insertion of two Tads here (NL) (in an orthodontic practice!) would amount to about 250 euro.

    • Dear Roelof Potgieser,

      I agree with you to 100%, any health economic analysis needs to be interpreted with caution. As you say has every country its own specifications and every economic model is built on a number of assumptions.

      We tried to address this by even reporting variables such as “number of appointments”, “treatment-chair-minutes” and “treatment duration”. These variables could be used to easily calculate with your own per-minute costs.

      Funny how is the cost of 250 € that you describe quite close to the difference in material costs that we calculated (233 €). As a clinician, we can often specify the direct material costs. However, it is easy to forget the surrounding costs: You use sterile instruments, the treatment room has to be prepared with sterile equipment and it has to be cleaned afterward. In other words, there is a hidden procedural cost related to miniscrews.

      Furthermore, when using skeletal anchorage, space closure follows a unilateral pattern resulting in half the speed of space closure.

  3. is that description of molar block anchorage as they wrote it?

    For molar block anchorage they tie the second molar, first molar and first premolar together with ligatures to provide an anchor unit to retract a first premolar.

    If the first premolar is ligated to first and second molar then how is it retracted? Do they mean retracting a canine by ligating the second premolar to the molars?

  4. This is interesting and useful data.
    I tend to use tads/boneplates in non-extraction cases mainly ( adult retreatments commonly) but this is still interesting. My only comment would be that to put 2 tads in is quick and relatively inexpensive, and it would seem that they were used in pts that didn’t need them just to find numbers??

    • Dear Robert Wakefield,
      I understand that the sample we used in our trial can be a bit confusing: why should one use skeletal anchorage in a sample that does not need maximum anchorage?! Well, we thought that the question of whether skeletal anchorage is capable of good anchorage reinforcement has been evaluated in a number of well-conducted trials.
      Miniscrews deliver good anchorage reinforcement. However, with a maximum anchorage sample, you could only compare techniques that definitely can deliver maximum anchorage. But, how do we know whether a standard treatment could benefit from this technique?

      I would interpret our results in this way: When good anchorage reinforcement is needed, miniscrews are superior. This superiority has a price that is acceptable because you could not treat the case in another way. Will miniscrews completely replace other “inferior” techniques, i.e. should every case with moderate anchorage need be treated with miniscrews? Possibly not.

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