Let’s get this straight: the evidence on retainers

In this blog, 15 year old Liv talks about the struggle to keep her teeth straight after orthodontic treatmentSomething done with the aim of improving health or relieving suffering. For example, medicines, surgery, psychological and physical therapies, diet and exercise changes. and looks at new evidence on how well retainers do the job. 

Page last updated 23 February 2022

Take-home points

Getting my teeth straightened was a MASSIVE deal. My front teeth were crooked. To the orthodontist, it was a small defect; to me, it was the thing I was most insecure about. It made eating uncomfortable too. When I got them straightened, two years ago now, I felt so different, so confident!

Getting my brace had been a euphoric moment! When the orthodontist said “yes, we can put a brace on those & straighten them out!” it felt like Christmas and I’d just got the present I’d always wanted. Throughout the process, I could see my teeth getting straighter, bit by bit. It was like running a race, getting closer and closer to the finish line, not caring that it hurt, because I was so focused on getting to the end. When the brace came off, it didn’t seem real! I couldn’t stop smiling!

My teeth were straight but would they stay straight?

I was made well aware that my teeth might shift back, but I thought it wouldn’t happen to me, if I did all the right things. It was going to be really important to wear a retainer at night and I was determined to wear it every night, come what may.

In the fortnight I was waiting for it to be made, I could feel with my tongue that my teeth didn’t make the perfectly smooth curve I’d felt when I first got the brace off. It was a struggle to make the new retainer fit and I was told to wear it all the time for the next week. After that, I wore it every night, but I had to bite down on it to keep it in place. It got holes in it and eventually snapped. In the time it took to make a new one, my teeth had shifted so much that it didn’t fit at all. Another had to be made. They gave me two this time, so I’d have a spare if one broke.

So, my retainer and I have a love-hate relationship! I like the fact that it’s comfortable in my mouth, soon after I’ve put it in, and that it doesn’t affect my speech. But I HATE how hard it is to clean. I still have to bite down a bit to keep it in place. They’re expensive to replace too.

Different retainer types

I’ve since learned that my type of retainer is a thermoplastic retainer. I just had what I was given, but I knew there were different types as my friends had retainers with a wire (if I’m honest, I was rather looking forward to choosing a pink sparkly one of those!). None of my friends with the wire types seem to have had the problems I’ve had with my retainer. So I was interested to hear that the Cochrane Oral Health Group has done a systematic review of the best evidence on retainers: Retention procedures for stabilising tooth position after treatment with orthodontic braces (published January 2016). Perhaps this could tell us (and our orthodontists) which type of retainer is best, or help people like me decide which might suit them best.

Here’s what I want from a retainer

1. It keeps my teeth straight
2. It’s easy to clean
3. It’s comfortable
4. It’s durable

If it’s durable, cost isn’t too big an issue perhaps, but it’s a consideration. Pink and glittery would be an added bonus, of course! Colour aside, is that all too much to ask? Do different types do an equally good job? Better look at the evidence.

How do different retainers compare?

The Cochrane review has evidence from 15 randomizedRandomization is the process of randomly dividing into groups the people taking part in a trial. One group (the intervention group) will be given the intervention being tested (for example a drug, surgery, or exercise) and compared with a group which does not receive the intervention (the control group).   controlled trialsA trial in which a group (the ‘intervention group’) is given a intervention being tested (for example a drug, surgery, or exercise) is compared with a group which does not receive the intervention (the ‘control group’). with 1722 adults and children, comparing different types of retainers. The review authors hoped to find out how the retainers compared for teeth stability, retainer failure (breaking, getting holes in them or being lost), unwanted effects on oral health and how satisfied people were with them.

Cochrane reviewsCochrane Reviews are systematic reviews. In systematic reviews we search for and summarize studies that answer a specific research question (e.g. is paracetamol effective and safe for treating back pain?). The studies are identified, assessed, and summarized by using a systematic and predefined approach. They inform recommendations for healthcare and research. always include an assessment of the quality of the evidenceThe certainty (or quality) of evidence is the extent to which we can be confident that what the research tells us about a particular treatment effect is likely to be accurate. Concerns about factors such as bias can reduce the certainty of the evidence. Evidence may be of high certainty; moderate certainty; low certainty or very-low certainty.  Cochrane has adopted the GRADE approach (Grading of Recommendations Assessment, Development and Evaluation) for assessing certainty (or quality) of evidence. Find out more here: https://training.cochrane.org/grade-approach and how much the research might have been subject to biasAny factor, recognised or not, that distorts the findings of a study. For example, reporting bias is a type of bias that occurs when researchers, or others (e.g. drug companies) choose not report or publish the results of a study, or do not provide full information about a study.. Most of the studies were assessed as low quality so it’s not clear how the retainers compare. But one studyAn investigation of a healthcare problem. There are different types of studies used to answer research questions, for example randomised controlled trials or observational studies., comparing full-time with part-time wear of thermoplastic retainers, had better (moderate quality) evidence. It suggests that wearing them part time rather than all the time probably makes no difference to teeth stability, but this finding could change when more research is available.

So that’s all this research can tell me about how well they keep teeth straight. How about the other things on my retainer wish list?

• Ease of cleaning: the studies don’t explore this
• Comfort: one study reported that more people were embarrassed by Hawley retainers compared with thermoplastic ones and found them harder to wear, but there isn’t strong evidence to help us choose between retainers
• Durability: again, no reliable evidence

So what difference does this make to choosing our retainers?

Not as much as I would like! Let’s hope that one day I’ll be doing a blog on this with more definitive evidence! Until then, we’ll carry on making a choice based on others’ experiences and/or what our orthodontists offer. The orthodontists working with Cochrane Oral Health identified this topic as high priority and I know it’s high priority for me and other ex-‘brace faces’! I hope we’ll see more and better research in the next update of this review.

Keep smiling!

Join in the conversation on Twitter with @CochraneUK, @CochraneOHG or leave a comment on the blog. Please note, we cannot give specific medical advice and do not publish comments that link to individual pages requesting donations or to commercial sites, or appear to endorse commercial products. We welcome diverse views and encourage discussion but we ask that comments are respectful and reserve the right to not publish any we consider offensive. Cochrane UK does not fact check – or endorse – readers’ comments, including any treatments mentioned.

Liv Chapman has nothing to disclose.

Links:

Littlewood SJ, Millett DT, Doubleday B, Bearn DR, Worthington HV. Retention procedures for stabilising tooth position after treatment with orthodontic braces. Cochrane Database of Systematic ReviewsIn systematic reviews we search for and summarize studies that answer a specific research question (e.g. is paracetamol effective and safe for treating back pain?). The studies are identified, assessed, and summarized by using a systematic and predefined approach. They inform recommendations for healthcare and research. 2016, Issue 1. Art. No.: CD002283. DOI: 10.1002/14651858.CD002283.pub4.

Plain language summary of this review: http://www.cochrane.org/CD002283/ORAL_what-best-method-maintaining-correct-position-teeth-after-orthodontic-treatment

Cochrane Oral Health. “Retaining tooth position after orthodontic treatment”. Cochrane Oral Health Editorial Base Blog, 4^th February 2016. Web. 22^nd February 2016. https://cochraneohg.wordpress.com/2016/02/04/retaining-tooth-position-after-orthodontic-treatment/