An occasionally irregular blog about orthodontics

Myofunctional orthodontics continued: A new trial!

Myofunctional orthodontics continued: A new trial!

Myofunctional orthodontics continued… a new trial!

This post follows on from last week’s very popular blog which was read 2,500 times in a week. In that post I wrote that I was only aware of one prospective study of Myofunctional therapy. But Valter Ronnholm,  posted a comment that pointed me to a new study in the European Journal of orthodontics advance publications.

One-year treatment effects of the eruption guidance appliance in 7 to 8-year-old children: a randomised clinical trial.

Rita Myrlund et al

European Journal of Orthodontics: Advance publication


This paper was published by a team based in Norway who wanted to investigate the effectiveness of an eruption guidance appliance on the teeth of children in the North of Norway, where travelling distances make treatment difficult. This is why I have illustrated this post with a picture of Norway.

Unknown-2What did they do?

This was a randomised controlled trial. They enrolled 159 7-9 year-old children from one municipal town. The children were screened for malocclusion and then 48 were selected to take part in the study. These children were randomised into treatment and control groups. Randomisation was done by drawing lots and allocation concealment was good. The groups were balanced for age at the start.

They treated the children who were in the treatment group with an eruption guidance appliance. They wore the appliance all night and two hours during the day. At the end of the study they collected study models and cephalograms for both groups. After one year they collected study models and cephalograms for the treatment group and study models only for the control group.

What did they find?

As there were no radiographic measurements for the control group it was not possible to make any cephalometric comparisons. So I shall only discuss the study model measurement.  I have reproduced the important measurements in this table for the end of treatment only.

Overjet (mm)2.8 (2.1-3.4)5.2(4.6-5.7)
Overbite (mm)2.1 (1.5-2.6)4.6(4.1-5.0)

I calculated the 95% CIs from the data. This shows that the 95% confidence are wide in comparison to the size of the overjets that were measured. This indicates that there is some uncertainty in the data, but I would expect this from a small sample.

Crowding was measured as being present or absent.  I have included the relevant data in this table.

Crowding (yes/no)TreatmentControl

This shows that the appliance was effective for the correction of mandibular crowding.  I also calculated the numbers needed to treat and this showed that to reduce mandibular crowding for one patient you needed to treat 3 patients, but for maxillary crowding you needed to treat 21 patients to correct crowding in 1 patient.

It appeared that the use of this appliance reduced overjet, overbite and mandibular crowding. In the discussion the authors pointed out that these effect sizes were small, but they were clinically significant. Overall, they concluded that the eruption guidance appliance may be an effective interceptive appliance.

What did I think?

I thought that this study was very interesting and I am looking forward to the long term follow up, which they are currently working upon

There are several important points to be considered when we interpret this paper. Firstly it appears that the starting malocclusions were mild,for example, the mean overjet was only 5 mm. However, there is no doubt that these were corrected. Nevertheless, I would really like to see the results of treatment are achieved when children with more severe problems are treated.

This study was well carried out and very simple. It was also important, and interesting, to see that the cooperation was high with only two dropouts per group. This is much lower than failure rates reported in a randomised clinical trials of the functional appliances, for example the Twin Block when figures of 15-20% have been reported.

In summary, this was a study that provided very useful information on a form of  treatment that appears to be effective in the short term.  I would really need to see some long-term results before I change my practice. But as I said last week there may well be something to this treatment and the evidence is beginning to build.

You may remember in my last post I asked if the proponents of  myofunctional orthodontics would consider taking part in a prospective study.  They have done this and I will start working on this with them.  My offer of space on the blog still is open, if anyone wants to make any comments in a separate post?
Myrlund, R., Dubland, M., Keski-Nisula, K., & Kerosuo, H. (2014). One year treatment effects of the eruption guidance appliance in 7- to 8-year-old children: a randomized clinical trial The European Journal of Orthodontics DOI: 10.1093/ejo/cju014

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There Are 6 Comments

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  1. Mo Al-Saleh says:

    Way to go Kevin.

  2. Alfred C. Griffin, Jr. DDS says:

    “This shows that the appliance was effective for the correction of mandibular crowding. I also calculated the numbers needed to treat and this showed that to reduce mandibular crowding for one patient you needed to treat 3 patients, but for maxillary crowding you needed to treat 21 patients to correct crowding in 1 patient.”

    If I am interpreting this correctly, the inferred success rate for treating mandibular crowding with this appliance therapy is 33 percent and for treating maxillary crowding the inferred success rate is less than 5%. What threshold of success rate is appropriate to deem that a treatment modality is clinically efficacious?
    Thank you for your objective commentary.

  3. Dear Kevin;

    I commend you on your wish for a properly conducted RCT on this topic. The current lower level evidence in clinical trials shows ‘statistically’ significant effects but all such trials come to a ‘clinical’ change of ~1.5 – 2.5mm in overjet, ~2mm in overbite and ~2mm in crowding reduction. The study by Janson (AJODO 2007;131:717-28) in Brasil demonstrated that the overbite and crowding relapsed virtually back to their starting point and the overjet for 3 years of treatment maintained a ~1.5mm improvement. You then have to ask is this clinically significant especially considering the time involved. A previous RCT (Eur J Paediatr Dent. 2012 Sep;13(3):219-24) comparing a myofunctional appliance with an Activator found the Activator was more comfortable and when I contacted one of the authors, they had continued this RCT to evaluate the hard and soft tissue effects. The findings were presented as a poster at the 87th Congress of the European Orthodontic Society (Abstract book, scientific poster :361) and the abstract stated the following;

    1. The Activator group showed better skeletal improvement than the myofunctional group.
    2. The facial convexity improved significantly with the Activator and to a lesser extent with the myofunctional appliance.
    3. Soft tissue profile was improved by the Activator. This was not found with the myofunctional appliance.
    Conclusions: The Activator is more effective than the myofunctional appliance in treating class II div 1 patients.

    This is available here:

    This topic is interesting and worthy of further research as the claims made by some seem rather remarkable. To quote Carl Sagan; “Extraordinary Claims Require Extraordinary Evidence”.

    • Greg Spencer says:

      I just want to comment on a few aforementioned points. In regards to the study Peter sites, those are completely different products that are being used. In the above “Norway” study, they are using an Occlus-o-Guide that is basically a preformed activator and positioner. In the publication that Peter sites they are using a Myobrace T4K Trainer which is only myofunctional. This study would then give more credence to the appliance used in the Norway study since the EGA they are using acts more like a activator than just a myofunctional device.

  4. Lysle Johnston says:

    Dear Kevin
    The fact that it was an RCT does not confer a license to suspend disbelief. Given that bone cannot grow interstitially and given that there are no sutures in the mandible, one must assume that the overjet and crowding “corrections” were fueled by expansion and flaring.

    • Kevin O'Brien says:

      Dear Lysle, thanks for the comments. Yes, I agree that the changes that they reported are likely to be due to flaring and general tipping of teeth. Do you think that this is the same as for other “functional” appliances?

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