January 16, 2017

Oh no, orthodontic piezocision may cause root resorption! Do we need to be careful?

Oh no, orthodontic piezocision may cause root resorption! Time to think again?

An increasing amount of  research is being done into methods of making teeth move faster. One method is called orthodontic piezocision and this new trial shows that it may cause root resorption. But does it?

I have written about piezocision before. I concluded that we do not have evidence that this technique results in faster tooth movement. In order to come to this conclusion I critically appraised the studies. I am going to continue this approach with this new paper that was recently published in the American Journal of orthodontics.

shutterstock_158352575Effect of piezocision on root resorption associated with orthodontic force: A microcomputed tomography study

Braydon M. Patterson, et al

Am J Orthod Dentofacial Orthop 2017;151:53-62.  http://dx.doi.org/10.1016/j.ajodo.2016.06.032

A team from Sydney, Australia did this study.

It has been suggested that corticotomy accelerates tooth movement by the activation of a regional accelerated phenomenon (RAP). This may occur by increasing bone and periodontal ligament turnover following the trauma. This seems like a good idea.  Unfortunately, clinical research has not supported this hypothesis with any degree of certainty.

Orthodontic piezocision is an alternative to corticotomy.  This is more conservative than corticotomy, because you do not need to raise a flat. But again the evidence on its effectiveness is lacking.

In this paper the authors describe a pilot study in which they wanted to investigate the effect of piezocision on root resorption.

What did they do?

They carried out a small split-mouth study. The PICO was:

Participants: Patients having orthodontic treatment requiring the extraction of first premolars

Intervention: Piezocision

Comparator: No treatment

Outcome: Root resorption

They enrolled 14 patients.  For each patient they allocated the maxillary first premolar on one side to receive piezocision. The other side had no intervention.

This was not a random allocation. They selected the side with the least risk of root resorption. Unfortunately, they gave no information on how they took this decision.

They fitted a sectional fixed appliance from the first moment to the first premolar and applied 150 g of force in a buccal direction. They then carried out orthodontic piezocision to the selected premolar.

After four weeks of tipping they extracted the premolars. They then scanned them with an x-ray micro-tomograph and measured root resorption.

What did they find?

They included data on 14 patients yielding a total of 28 premolars. The scans revealed that the piezocision teeth have had an average of 0.435 mm³ root resorption compared to 0.133 mm³  for the control group.

They also noted that five teeth had considerable iatrogenic damage from the piezocision procedure and they added this to the resorption data. This resulted in the average root resorption for the piezocision group increasing to 0.633 mm³. They carried out some statistics which showed that these differences were statistically significant.

Finally, they concluded that piezocision may increase root resorption and cause iatrogenic damage

They pointed out that this was a pilot study and they did not randomise the split mouth allocation. There was also no blinding of the outcome assessment, but I was not clear on why this was the case.

What did I think?

Firstly we need to be very careful about how much we can conclude from this paper. This is simply because it is a pilot study. The main purpose of the pilot study is to to develop methods and obtain data in order to plan a larger study. As a result, we should not take much notice of any outcome data.  The authors pointed this out in their excellent discussion. I hope that they can carry out a further larger scale study of this important question.

Nevertheless, this does illustrate to me that there are some risks to using orthodontic piezocision and this damaged a fair proportion of the teeth. I think that this is an important pointer towards further research. Furthermore, we should bear this in mind when we are considering this untested treatment.

So what can we conclude?

As with all research I think a good way to consider the findings is to think about what we may say to a potential patient as part of consent. So for piezocision, all we can say is;

“I can make some cuts in your bones and gums that may make your teeth move faster. This technique has not been adequately researched. There are several small, low quality studies that show very small increases in the speed of tooth movement and also some damage to the roots of the teeth”.

You may feel that this sounds rather critical, but pass me the snake oil until some large-scale research is done.

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Have your say!

  1. Avatar

    Dear Kelvin
    Thanks for today’s posting, it’s quite interesting to note that piezocision also has side effect on root resorption.
    Hopefully more studies in the future will either agree or disagree with this report in future.
    My question ;
    In orthodontics,does the density of the alveolar bone play any role in the rate of resorption of the roots?

  2. Avatar

    Thanks again for another informative post.
    I like that with a Sydney based study, you have posted a photo of Luna Park as the gold standard!

  3. Avatar

    Thank you for presenting this topic. I think this study has some inherent flaws, though it is a pilot study and data cannot be applied to clinical situation. First, did they get IEC clearance, what benefit did patient get with this study. Second, is the duration of 4 weeks enough for clinically measurable root resorption. Third, mooving tooth buccaly is against cortical bone, which itself will initiate root resorption. In real clinical situation we move teeth through cancellous bone.
    Dr Elbe Peter

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