Do functional appliances influence skeletal pattern? More reviews giving us the answer!
I have just returned from the excellent AAO meeting in Orlando, where I met many followers of my blog. It was great to receive their feedback and I am genuinely surprised at how many people follow my postings. In this week’s post I’m going to review two systematic reviews on functional appliances. These were in the recent addition of the AJO-DDO. Both aim to identify skeletal effects of functional appliances.
Ishaq et al
AJO-DDO Volume 149, Issue 5, Pages 612–624
These investigators carried out a systematic review to evaluate the effect of fixed functional appliances combined with multi bracket appliances on class II skeletal pattern.
What did they do?
They carried out a systematic review of articles published until April 2014. They included papers reporting randomised clinical trials and non-randomised controlled clinical trials. Each study had to include an untreated control group. Their main outcome measure was cephalometric data collected at the end of the functional phase of treatment.
They assessed risk of bias with the Cochrane tool for RCTs. They used the Newcastle-Ottawa scale to assess the quality of the non-randomised studies.
They initially identified 1366 papers and after the usual filters they identified 5 trials. These were divided into 1 RCT, 2 quasi RCTs and 4 prospective controlled trials. There was some variation in the measurements used in the studies, nevertheless, they did extract data on relevant measurements. This data was not presented in the table and I found it a little difficult to follow.
In summary, they showed that the use of fixed fractional appliances when combined with multi-bracketed appliances did not have an effect on the skeletal pattern. However, the evidence was weak.
Nucera et al
This was a paper from a team based in Italy and Greece.
What did they do?
They carried out this systematic review to find out if there was an effect of removable functional appliances on maxillary growth.
They included studies that were randomised controlled trials and prospective controlled clinical trials that included an untreated control group. Again, the outcome measure was cephalometric measurements.
They carried out the usual search, filtering and assessment of risk of bias. They finally identified 14 papers. These were divided into 4 RCTs and 10 prospective CCTs.
What did they find?
They found that the main effect of functional appliances on the maxillary restraint was -0.61° per year. This was statistically significant. But my feeling is that this was not clinically significant
They also found that there was a mean difference of -0.61 mm in anterior maxillary displacement. There was no effect on maxillary rotation.
In the discussion they pointed out that they only found a small number of trials and this led to a large amount of variation in the data. Nevertheless they did conclude that removable functional appliances appeared to inhibit sagittal maxillary growth.
What did I think?
A few weeks ago I covered another systematic review on the effects of functional appliances on skeletal growth. You may remember that this was on the effects of fixed function appliances and the authors concluded that there was no influence on the skeletal pattern to a meaningful degree. It is interesting to see that these two papers have reached the same conclusion.
In the comments section of my previous post Carlos Flores-Mir pointed out that in the last 10 years there have been 25 systematic reviews on class II treatment. He also felt that the most important findings from any trial should be concerned with factors such as compliance and patient experience. I totally agree with him.
The authors of both of these papers made the “usual” conclusion to a systematic review that “more RCTs were needed”. I am not sure that I agree with this statement as it is now becoming very clear that functional appliance treatment does not influence cephalometric measures to a clinically important degree. Nevertheless, I think that if further trials are to be carried out investigators should evaluate other outcomes such as compliance, experience, socio-psychological factors, trauma and even breathing. These are far more important outcomes that are relevant to our patients.
I cannot help feeling that we are in danger of carrying out too many systematic reviews into Class II malocclusion based on cephalometric measurements. There appears to be a trend to review the effects of every individual functional appliance on every different facial bone! I am worried that we will soon be having systematic reviews of systematic reviews in the endless quest to find out if we can alter facial growth.
At this point I’m sure that the question has been answered. I will also not write another blog on a systematic review on the effects of functional appliances.
Finally, I will make a plea to investigators and Journal editors. Please make this stop….. and I do not think that CBCT will tell us any more than we know now!