Orthodontic Retention – finding the answer?
This is a guest post by Simon Littlewood on the difficult subject of orthodontic retention. He is one of the World’s experts on orthodontic retention. It is a really good read! Simon works in Bradford, North of England…
At a recent dinner party someone asked me what question I most wanted answered. Without hesitation I said “What’s the best way to retain our orthodontic results”. There were no other orthodontists at the party, so there was an embarrassing silence. As you are reading this post, this suggests that you are more interested than my dinner guests. So let me expand further.
Why is it so important?
There are many important questions in orthodontics, for example “how best to speed up treatment”, and “which is the best type of appliance?” Interesting questions, but they become less important if the end result relapses.
Relapse is often unpredictable. It also seems to continue over a long period. This leads many clinicians to advise their patients to wear retainers for “as long as they want straight teeth”. If we are asking for this sort of long-term commitment from our patients, we need to be sure the retainers do the job and are safe.
Providing evidence-based retention
An evidence-based approach means taking into account the best research evidence, clinical expertise and patient’s values, expectations and circumstances. Our Cochrane Review looking at the best research evidence for retention last year concluded:
“We did not find any evidence that wearing thermoplastic retainers full-time provides greater stability than wearing them part-time”
Secondly, we found that there was insufficient high quality evidence to make further recommendations. This second conclusion often frustrates clinicians (including me!). However, this is due to Cochrane’s use of a stringent quality assessment called GRADE (Grading of Recommendation, Assessment, Development and Evaluation). This means we can only make firm conclusions if we are certain that we can trust the result, and that any further research in this field is unlikely to change our conclusions. As a result, I have learnt to read beyond the conclusions of Cochrane reviews, as there is often lots of other useful information in the review that I can use clinically. Kevin O’Brien has nicely summarized the retention Cochrane Review in a previous blog.
Are RCTs the only way to investigate retention?
RCTs remain the gold standard for comparing different interventions, for example, different types of retainers or even comparing retainers to no retention at all. Retrospective research, while generally easier to undertake, is subject to more bias and we can therefore be less confident in the findings. However, one area where retrospective studies are useful is in reporting unusual side effects. An example in retention research is the unwanted side effect of bonded retainers that become active and can lead to compromised periodontal support.
How can we research patients long-term?
Most current retention RCTs provide information after 6-24 months. This is useful information, but with life-long retention, it only gives us some of the answers. Recalling patients years later to measure relapse is difficult. Perhaps, we need a smarter way of following patients up in the long-term. In an era of smartphones, apps and selfies, I wonder if there is a better way to monitor long-term post-treatment changes?
Are we asking the right questions?
Our main outcome measure in the Cochrane retention review was Little’s Irregularity Index. This has its imperfections, but for most clinicians this provides an understandable measure of crooked teeth. But is this important to patients?
Asking patients to wear retainers indefinitely adds to the burden of their care. They have to be responsible for wearing and looking after the retainer, as well as getting it checked, repaired and replaced, which may have financial costs. Patients may be more interested in ease of use, costs, comfort, how simple it is to look after, and whether the retainer keeps their teeth straight enough for what they want.Future research with patients may identify what is really important to them about retainers. We should then use this information as an outcome in trials, along with our more traditional measurements of stability.
Retention research – is it worth it?
We’ve already established that retention research is challenging, so is it worth the effort? The answer of course is yes, particularly if we focus on outcomes that are important to our patients. This is because almost everything else we do in orthodontics is compromised unless we can hang onto the result.
I need to know the best way to retain my orthodontic result for every one of my patients. I also need to know so that I don’t embarrass myself at future dinner parties. If I ever get invited again…
Emeritus Professor of Orthodontics, University of Manchester, UK.