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.
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.
What 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.
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
Emeritus Professor of Orthodontics, University of Manchester, UK.