Simple removable appliance expansion is effective?
Recently, there has been an increased interest in the expansion of the maxillary dental arch. This has involved the development of seemingly more complex methods of expansion. But have we forgotten that simple techniques may also work? This new paper looks at maxillary arch expansion with a simple removable appliance. It is not perfect, but it is worth considering.
Maxillary arch expansion appears to be becoming increasingly complex with the development of RME, Hybrid RME, Maxillary Skeletal Expansion and other methods. All these methods promise both dental and skeletal expansion. Orthodontic gurus are making claims on the use of these appliances and their effect on the airway. We have discussed these in earlier blog posts. Sometimes, I wonder whether we forget the simple methods of orthodontic treatment. Although, I will concede that I may sound like an old Professor reminiscing about the old days and our techniques. Nevertheless, this new paper has made me think about the way that we used to correct crossbites.
A team based in Leuven, Belgium, did this study. The European Journal of Orthodontics published the paper.
What did they ask?
They did this study to determine if a simple removable expansion appliance was effective at interceptive treatment of anterior and posterior crossbites
What did they do?
They did a short-term prospective cohort study of simple removable appliance expansion.
The inclusion criteria for the patients were that they were receiving expansion treatment for crossbite, lack of space, canine impaction and functional shift. The patients were all in the mixed dentition. They also had to have complete records of photographs, digital dental casts, panoral and cephalometric radiographs at the start and end of treatment.
Resident/postgraduate orthodontic students provided the treatment using a removable appliance expander with a midline screw, molar capping and a labial bow.
They used slow expansion, and the patients turned the midline screw at a rate of 0.25mm expansion a week. They continued this treatment until they had corrected the transverse problems.
At the end of the expansion, they asked the patients to continue to wear their appliances for two months of full-time passive wear and two months of part-time wear. They did the final data collection after this period.
The primary outcome measure was whether they had corrected the crossbite. The other outcomes were whether a functional shift had been corrected and the sagittal relationship of the molars.
What did they find?
The authors presented a large amount of data, and I shall concentrate on what I feel are the main findings.
They enrolled Two hundred seventy-four patients into the prospective cohort. Unfortunately, 48 did not meet the inclusion criteria because of a lack of records, non-compliance or change to an external orthodontist, a dropout rate of 17%. I shall return to the implications of this later in my post.
The mean age of the patients at the start of treatment was 8.7 years.
At the end of treatment, 98% of the patients had their crossbite corrected. The mean increase in intermolar width was 3.8mm.
Their final conclusion was:
“A removable appliance plate was effective in improving the transverse dental dimensions of the maxilla in the mixed dentition”.
What did I think?
I thought that this was an ambitious study that required a lot of careful treatment and data collection. While it is not an RCT, its prospective nature provides a reasonably high level of evidence. As with most studies, there were some limitations. These were, firstly, they lost 17% of the original patients because of dropouts. This problem meant that the study suffered from selection bias, particularly concerning non-cooperation. If they had included the data from these patients in the analysis, I am sure that it would have changed the results.
Furthermore, there was no untreated control. As a result, we cannot discount that some of the crossbites may have self-corrected.
Nevertheless, the findings do illustrate that this simple interceptive treatment is highly effective for dental crossbites. Furthermore, it may be that general dental practitioner can do this treatment. However, in an earlier study, the authors suggested that specialist practitioners are more effective than generalists.
We also need to remember that this is a short-term study. I am interested in seeing the long-term follow-up to this study as I am sure that the results will be fascinating and clinically relevant.
Finally, it is interesting to consider this treatment compared to much more invasive treatments, for example, MARPE. We could use a removable appliance for the straightforward dental case rather than screwing expansion devices into young children. This question would be an excellent subject for a trial.
Since publishing this post, I have received some great comments. Most of these have pointed out that when we expand we are looking for skeletal change. In this respect, my comments on MARPE are misplaced. I have looked at these again and I wonder if was being a bit too “dry” when I commented. I certainly agree that when we want skeletal change then we should use the best skeletal expander. However, when we just have a dentoalveolar problem then we can use a simpler method. I feel that my comment was directed at the “expand at all costs with as complicated method as possible” orthodontist.
Emeritus Professor of Orthodontics, University of Manchester, UK.