An occasionally irregular blog about orthodontics

The World Cup is over: now get back to work and read this blog on interceptive orthodontics!

By on July 15, 2014 in Clinical Research, Trials with 1 Comment
The World Cup is over: now get back to work and read this blog on interceptive orthodontics!

Interceptive orthodontics:  Get back to work and read about orthodontics!

Now that the World Cup is over, I can get back to work. It has been good to see that the blog readership has only dropped slightly since I reduced the number of my postings due to World Cup commitments. Or maybe more people were watching the World Cup  than reading my blog?

This post is on interceptive orthodontics. Previous readers will know that this is an area that has always interested me and I have posted on this before (see previous blogs on interception and Class II treatment). My last post on this subject attracted a lot of interest and I even got a bit of criticism because some readers felt that I had not been sufficiently critical of the paper that I reviewed. A new paper from a Norwegian based team has been published in the advanced publications section of the European Journal of Orthodontics and I am going to review this carefully. Unfortunately, it is behind the EJO paywall, so if you are not a member of the EOS or can get access through a library etc, you cannot read it…


Eruption guidance appliance

Eruption guidance appliance

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

European Journal of Orthodontics

Myrlund R et al




In their introduction they cover the area of early interceptive treatment very well and quote classic studies. This was a nice balance between personal opinion, and higher levels of research. They also drew attention to the studies that  out in Finland (see blog).

They then outlined the Eruption Guidance Appliance (EGA). This is a combination between a functional appliance and a positioner. The appliance aims to achieve sagittal correction and alignment at the same time and I thought that this was an interesting and logical approach.

The aim of their study was to evaluate the effectiveness of a 12 month course of EGA treatment in achieving a “normalization” of the occlusion. This was a simple aim which essentially meant “wouldn’t it be great if we could just fit a simple appliance out of a box to children and prevent the development of malocclusion”. No-one would complain at that!

What did they do?

They carried out a small trial, which had a sample size calculation, good concealment and randomization and the examiners were blinded to allocation.

They screened 159 7-8 year old children from one municipal dental clinic in Tromso, Norway. They were looking for children with features of developing malocclusion.

They calculated that they needed 20 subjects in each group. They randomized 48 patients to receive treatment with the EGA or to an untreated control.

The patients wore the EGA when they slept and for a limited time during the day, for a 12 month period. They are now being followed up as part of a future study, but they did not state when the follow-up would end.

They collected data at the start of the study (T1) and after a 12 month period (T2). They took study models of both groups and made dental measurements. They also took cephalograms for all the subjects at T1, but they took them at end the study for the treatment group only.

What did they find?

They presented a large amount of data that they recorded from the study models and the cephalograms. I have decided not to discuss the cephalometric data for two reasons, firstly they only took radiographs at the start and finish of treatment for the treatment group. As a result, the changes were not compared to the control and they may have occurred without treatment. Secondly, many of the differences that they reported were small and their statistics were prone to Type I errors, as I have outlined in a previous posting on “cephalometrics in research”.

The study model data was relevant to the aims of the study and was more interesting. In effect, they found that for most of the dental measurements the EGA had an effect. Nevertheless, the differences were small, for example, the difference in overjet between the EGA and control group was 2.4mm. They did not present confidence intervals for the data and I calculated this for the overjet measurement. The 95% confidence interval was 3.2-1.6. This means that if the study were repeated; 95 times out of a 100 the difference could be 3.2mm or as low as 1.6mm. I interpreted this to suggest that this means that there was a high level of uncertainty about this difference (blog). This is likely to be due to the small sample size of the study, even though it had sufficient power.

What did I think?

When I first saw this study I was very interested in their findings. However, there are some issues with the study. These were

1 The sample size was small and this contributed to the wide confidence intervals; suggesting that there is a high level of uncertainty.
2 The effect size of the treatment was small and I am not sure that these were clinically significant.
3 I also wonder if the small sample resulted in a lack of variation in the sample

However, I feel that the authors have reported their finding with respect to these issues and they have cautiously stated that EGA may have an effect. We cannot be certain of any of the potential benefits of treatment until the patients have been followed up for a longer period, ideally when they have all completed adolescent orthodontic treatment. It will only be at this point when differences in treatment times, reduction in need and complexity of treatment can be evaluated. This is the method that the long-term Class II studies adopted.

Tromso, Norway

Tromso, Norway

This study was very similar to previous studies carried out in Finland. Importantly, these were done  in relatively small communities, where screening and interceptive treatment may be carried out. I am a little uncertain whether this could be achieved in larger populations, such as Manchester. But it may be worth it if true benefits are shown from these studies.


In conclusion, we still know very little about the effectiveness of interceptive orthodontic treatment. What we do know is that it may “work” but our level of uncertainty is still high. Nevertheless, this is very interesting and important research and these authors should be congratulated on this study and encouraged to continue and expand this work.
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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  1. Peter Miles says:

    Hi Kevin; Interesting reading as always and a very consistent result when compared with the other non-randomised studies on such myofunctional appliances all finding a 1.5 – 2.5mm change in overjet. As you mention it will be interesting to see if they find this change stable over time compared with the controls. I would also be interested in surveying the participants to find out whether those receiving treatment felt they were any better off than the controls – in other words what they went through was worth a 2.4mm change both initially and longer term (if it holds up)?

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