Our teeth move throughout our lifetime. When teeth shift after orthodontic treatment it is called orthodontic relapse. It is normal and expected that teeth will shift after orthodontic treatment if retention is not used. Unfortunately, many people learn the “retention lesson” the hard way. Once you’ve experienced orthodontic relapse at least once, it tends to make you more motivated to use retainers.
If you’ve recently completed clear aligner therapy but gotten off track with your retainers, it may be tempting to re-use your old aligners. Should you?
During treatment, we instruct patients to keep their last set of aligners when they move on to a new set. The only time you should re-use an old aligner is if you lose or break your current set. Going back to the previous set will as least ensure you do not lose the progress you have made while replacement trays are being fabricated.
Clear aligners are precision medical devices. Each aligner tray moves the teeth between 0.1mm and 0.25mm. Anything more aggressive than has the potential to damage the tooth by applying too much force too quicky. Pressures are applied very specifically to accomplish certain movements, including:
With movements this precise, the aligner must fit the tooth perfectly to accomplish the desired movement. The problem with re-using old aligners trays is that we have no way to know:
• Which teeth have moved
• How have they moved
• How far have they moved
The only way to know with certainty is to take a new model of the teeth and essentially start the treatment process over.
There are two main dangers associated with re-using old trays:
1. They may apply too much force to a tooth, causing damage
2. They likely won’t fit properly which could cause teeth to move in unexpected – and unwanted – ways.
Your best option to avoid shifting teeth is to get in the habit of wearing retainers. If your teeth do shift, clear aligners are a great way to get that smile back where you’d like. But re-using old aligners is never a good idea. The sooner you address it, the easier and quicker your treatment is likely to be.