Is it better to use a fixed or removable appliance to correct a crossbite?: The final answer!
What is the best method of crossbite correction: The answer!
A few months ago I posted on the results of a trial of methods to correct anterior crossbites. Since then I have found several other papers from this trial and I have rewritten my original post to combine the findings into a single definitive post on the effectiveness of anterior crossbite correction.This new post is based on these four papers by Anna-Paulina Wiedel and Lars Bondemark.
A randomized controlled trial of self-perceived pain, discomfort, and impairment of jaw function in children undergoing orthodontic treatment with fixed or removable appliances. doi: 10.2319/040215-219.1
In these papers the authors have reported sections of a clinical trial that investigated the effectiveness of fixed or removable appliances for the correction of anterior crossbite. I think that they have published their findings in this way because this is the tradition in the Swedish Ph.D. thesis However, this does make overall interpretation of the findings a little difficult.
What did they ask?
The introduction was very relevant and concise. They raised a very simple question which was
“Is it more effective to use a removable or a fixed orthodontic appliance to correct an anterior crossbite”.
What did they do?
They carried out a very simple randomised trial in which 64 patients were randomised to receive treatment either by a removable appliance or fixed appliance. Randomisation concealment and blinding were good. Two specialist orthodontists and a post-graduate student under supervision treated the patients.
The removable appliance was a standard acrylic plate with a spring to procline the upper incisor. The fixed appliance was bonded to the anterior teeth and the primary molars or premolars, if they had erupted.
They collected data at the start and end of treatment and they analysed the data from all the patients regardless of the outcome.
There was an adequate size calculation and the statistics were simple univariate tests. Although, if I was being very critical I would have liked to see a multivariate analysis. Nevertheless, they adopted simple outcome measures and the groups were matched at the start.
All the papers were well written and mostly conformed to CONSORT guidelines. They randomised 62 patients into the two groups and all but one completed the trial.
1. Success rate and the outcome of treatment
For this part of the study the primary outcome measure was whether (or not) they corrected the crossbite. Secondary outcome measures were the treatment duration and dropout rate.
They found that all the crossbites in the fixed appliance group and all except one in the removable appliance group were corrected. Therefore, in terms of the primary outcome measure there were no differences between the two treatments.
However, they did find that the average duration of treatment was 1.4 months shorter with fixed appliance The average treatment time being 6.9 months for the removable appliance group and 5.5 months for the fixed appliance group.
It was clear that there were no differences between the two appliances. The difference in the length of treatment was not really clinically significant.
2. Pain, discomfort, and the impairment of jaw function.
They found that, in general, the intensity of pain was low to moderate for both groups. In the first few days the pain was greater for the fixed appliance treatment. However, when I considered the overall levels of reported pain, I felt that there were no differences between the groups. When they looked at jaw function they found that speech was influenced by the removable appliance. Whereas, the fixed appliances resulted in more difficulty in biting and chewing. There were no differences in appearance.
In summary, there were no differences between the appliances.
3. The costs of treatment.
In this part of the study they calculated the direct costs (material, time, and manpower) for each treatment using standard costing methods relevant to Sweden. They also calculated indirect costs. These are the costs to society, for example, loss of income assuming that the patient’s parents were absent from work. The overall cost included the cost of any re-treatment
|Bleeding on probing||Probing Depth||Gingival Index||Plaque Index|
|Treatment||49.2 (40.5-57.8)||2.53 (2.4 – 2.59)||1.42 (1.3 – 1.5)||0.87 (0.73 – 1.0)|
|Control||69.1 (59.8 – 78.3)||2.64 (2.57 – 2.7)||1.61 (1.49 – 1.72)||1.17 (0.96 – 1.31)|
They concluded that the costs of the removable appliance treatment were greater than those for fixed appliance treatment. This was mostly because of the higher costs of material and the increased number of visits with removable appliance therapy.
Finally,they followed the sample of children for 2 years and measured the stability of crossbite correction. They made several dental measurements from study casts using digital calipers. They found that relapse had occurred in two fixed and one removable appliance treatments. As a result, the outcomes were comparable. Even though some would say that twice as many of the fixed appliance treatment relapsed than the removable!
What did I think?
I thought that this was a really interesting and well carried out small study. It is also a great example of how a common clinical question can be answered with minimal resource and yet provide very useful information.
Importantly, they showed that there were minimal differences between fixed and removable appliances, when used for the correction of anterior cross bite. The only difference was cost, as the removable appliance treatments was more expensive than the fixed. As a result, I shall continue to use fixed appliances for anterior crossfire correction.
I only have two concerns. Firstly, the sample size calculation was based on one variable (treatment duration). As a result, the study may not have had sufficient power to differentiate statistically for the other outcomes. Nevertheless, when I looked at the magnitude of any differences they were not clinically significant.
I was also concerned that this study was published in four parts. I would really like to see one paper reporting and discussing all the data. Nevertheless, I hope that I’ve summarised it well enough for you to find this useful.
Wiedel, A., & Bondemark, L. (2014). Fixed versus removable orthodontic appliances to correct anterior crossbite in the mixed dentition–a randomized controlled trial The European Journal of Orthodontics, 37 (2), 123-127 DOI: 10.1093/ejo/cju005
Wiedel, A., & Bondemark, L. (2015). A randomized controlled trial of self-perceived pain, discomfort, and impairment of jaw function in children undergoing orthodontic treatment with fixed or removable appliances The Angle Orthodontist DOI: 10.2319/040215-219.1
Wiedel, A., Norlund, A., Petren, S., & Bondemark, L. (2015). A cost minimization analysis of early correction of anterior crossbite–a randomized controlled trial The European Journal of Orthodontics DOI: 10.1093/ejo/cjv026
Wiedel, A., & Bondemark, L. (2015). Stability of anterior crossbite correction:
The Angle Orthodontist, 85 (2), 189-195 DOI: 10.2319/041114-266.1
Emeritus Professor of Orthodontics, University of Manchester, UK.