Where do you keep your retainers? I like to recommend my patients keep theirs close to the bed so that they can be easily and quickly reached before going to sleep at night. Recently, a few patients have come in for a retainer check and noticed that their retainers are slightly distorted and not fitting around their teeth properly. After a little investigation (and revealing information on retainer storage locations!) I think I may have found a culprit.

The mystery

Over the years, I have had a few patients that have come to see me for retainer reviews and during examination, found that their Essex retainers do not fit as well as they should. The patients do not usually mention a problem but when examining the fit of the retainers, there are gaps present because the retainers are wider than when they were fitted and do not fit closely at gum level. The first time that someone brought this to my attention, I was perplexed but after a few other patients presented the same problem, I decided to ask some more questions.

Sherlock goes to work

When reviewing my second case of distorted retainers I asked about where the retainers were stored during the day and on every occasion, I found that when casting their minds back, the patient would remember leaving their retainers in one of 3 places:  A window sill, near a radiator or another place in direct sunlight or heat source.  The retainers generally sit with the bite surface pointing upwards but whether they are left one way up or the other, heat will lead to the same response, melting or distorted retainers. On further research, I found a small but quite varied selection of experiences online. Some had suffered from a similar experience to those I had seen and some had experienced a heat wave of 40 degrees but noticed no change in the fit of retainers. Perhaps direct or close intense heat sources may be the necessary trigger for this but I have not come across any research that investigates this problem. I suspect that this is because it is an occasional issue.


When fitting retainers, my team and I usually mention storing them in a cool place, but on review, this communication is probably not thorough enough. Some patients think of a bathroom as a cool place but once hot and steamy after bath time or with windows in direct sunlight, the room represents a risk. With this in mind, I think that clearer communication on the effects of direct heat is needed to ensure that patients store their retainers in the right places and avoid distortion of these thermoplastic pieces of plastic.

Note to readers

I have looked through retainer advice sheets and so far I have not found any reference to this problem.  Is there anyone else out there who has seen this phenomenon?