Removable functional appliances do not change skeletal pattern to a clinically meaningful amount
Functional appliances do not influence skeletal pattern…
This post is on functional appliances, which is an area that I have covered several times.
A few postings ago I mentioned that the journals are publishing more and more systematic reviews. I also made the point in a previous post, that we need to critically read these reviews because they are of variable quality, despite being published in the refereed literature. We have recently published a Cochrane review into Class II treatment and I was, therefore, very interested in this new review that was published in the EJO. This is, unfortunately, behind the EJO paywall, which restricts the availability of useful clinical information.
Vasilis Koretsis et al
EJO 2014, 1-7. Advanced access
What did they want to do?
The authors aimed to assess the effects of removable functional appliances in treated vs untreated patients using outcomes from radiographs. Bearing in mind my comments about radiographs and research, I did start reading this paper with a degree of trepidation, as I feared that I was entering a morass of cephalometrics. However, I was pleasantly surprised and I thought that this was an interesting and relevant review.
When I started reading I did become concerned because they did not confine the review to RCTs and included prospective non-randomised controlled clinical trials. As a result, we need to bear in mind that this is not as high a level of evidence as a Cochrane review, which only includes randomised studies. However, reviews of this nature do have a place, as long as we remember this shortcoming and interpret them accordingly.
What did they do?
They outlined their methods in a very clear way. It was good to see that they carried out a quality assessment of the literature that they included. They did this by assessing the RCTs with the Cochrane risk of bias tool and the CCTs with a similar instrument. They finally used the GRADE methodology to evaluate the overall strength of evidence from the review.
What did they find?u
They included 17 studies and these were divided up into 7 RCTs and 10 CCTs. They carried out a series of planned meta-analyses. These were clearly set out.
They concluded that when the effects of removable functional appliances were compared to no treatment, the following differences occurred
They also found that the Twin block was the most effective appliance, when compared to others.
The strength of evidence according to GRADE varied from moderate for SNA change to very low for ANB change.
They finally concluded that the skeletal effects of RFAs are minimal and of negligible importance. Most of the change was dental.
What did I think?
I thought that this was an interesting review that came to good sensible conclusions. I was a little concerned about the inclusion of CCTs, particularly when there was an adequate number of RCTs to draw some conclusions. However, they did report this in sufficient detail for the critical reader to interpret the evidence that they presented.
I did disagree with one of their conclusions when they stated that “more research is needed”. I cannot help thinking think that we have enough research from trials and systematic reviews to conclude that
“WE CANNOT GROW MANDIBLES OR RESTRICT MAXILLARY GROWTH TO CORRECT SKELETAL DISCREPANCIES WITH REMOVABLE FUNCTIONAL APPLIANCES TO A CLINICALLY MEANINGFUL DEGREE”.
I actually think that it is time to move on…….I now wonder whether it is necessary to carry out any more studies on the cephalometric effects of removable functional appliances. This review systematically covers a large amount of the published literature and it pretty much says it all….
Can we say the same for fixed functional appliances? I have seen no reason to say otherwise…
Does this finding help us in practice, when we see a patient with a Class II malocclusion. If the skeletal discrepancy is mild to moderate then I would be fairly certain that if I used a functional appliance I could obtain a good result from a combination of dental movements and some favourable growth. But what if the skeletal discrepancy is severe? I think that I would treat with a functional, but I would warn the patient and parent that they will still have a skeletal problem and this may need surgical correction in the future. Does anyone one to contribute to this discussion on this dilemma?
Koretsi, V., Zymperdikas, V., Papageorgiou, S., & Papadopoulos, M. (2014). Treatment effects of removable functional appliances in patients with Class II malocclusion: a systematic review and meta-analysis The European Journal of Orthodontics DOI: 10.1093/ejo/cju071
Emeritus Professor of Orthodontics, University of Manchester, UK.