Retention and Retainer Fatigue

Retention

Ask any orthodontist what the hardest part of their job is and there is no doubt, in my mind, that a very popular response will be retention.  There are several possible “phases” to orthodontic treatment. Some patients may go through two-phase treatment in which there is a phase I, where we are very focused on fixing a specific problem before all of the adult teeth are in, and a phase II treatment for comprehensive bite correction. I believe we should consider retainer wear as phase III of orthodontics, because it is just as important as any other phase of treatment. I am sure many of you are reading this and thinking, “When I went through braces I was told to wear my retainer for a certain amount of time and then it was no longer necessary.” Let me tell you why this is a bad idea!

Clear Retainers with Typodont

In many regards preventing teeth from moving is the hardest facet of orthodontic treatment. Your teeth are not unlike anything else in your body, they are set in bone and surrounded by tissue and ligaments. Bone is not like cement. Bone can, and will, change and if you don’t actively maintain the final position of your teeth, they will move. What I cannot tell you is how much they will move. A great example of this (many of you may have already heard this from me while in the office) is the difference between my wife, Kelly, and me. Kelly was treated with upper only braces and rarely wore her retainer for the better part of 10 years and her teeth barely moved. I have gone through initial treatment and two rounds of Invisalign because if I don’t wear my retainers I can feel my teeth move throughout the day! My teeth want to move whereas Kelly’s do not. She is lucky! The major problem is that I have no way of identifying who will experience relapse and who will not, but I can say if you are wearing your retainers, you will have less relapse than someone who does not.

Retainer Fatigue

I also want to touch on the importance of replacing your retainers. Clear retainers are our retainer of choice for several reasons: they look better (and hopefully are worn better), and hold the teeth in their position better than the traditional Hawley retainer. However, there is one downside to these retainers – the plastic fatigues. Every time you remove your retainer you are stretching the plastic just a tiny bit. Over time the plastic stretches enough to allow micromovement of your teeth and as these movements get larger and larger the retainer stretches more and more. This is the reason why some people come in after wearing their retainer faithfully still have experienced some minor relapse of their teeth. Believe it or not your teeth are stronger than a thin layer of plastic. Crazy, I know! If you were to take a person who had been wearing their retainers faithfully for a year and gave them a brand new retainer made off of their original models, that new retainer would be much tighter than the old retainer due to plastic fatigue.

Lost Retainers

I can’t tell you how often to replace your retainer because there has never been a long term study on what happens to the retainer plastic over time. Our suggestion at TDR is to replace your retainer every 18-24 months (or sooner if they are getting the funk). If I had the ability to give someone a pill that would eliminate tooth movement (and retainer wear) I would do it in an instant. There is a substance that has been shown to reduce tooth movement when injected around the teeth; however, it has only been used on lab rats and will not reach consumers anytime soon.

The moral of the story? Wear your retainers and replace them regularly for the best chance of keeping your teeth as straight and beautiful as the day your braces were removed.

Thanks for reading!

Dr. Groth