Most old Invisalign trays can be thrown away, but you should always keep your most recent set as a backup in case your current tray or retainer is lost or damaged. Beyond that, your options are limited: aligners are made from a multi-layered plastic that can’t go in your curbside recycling bin, and repurposing them for things like teeth whitening isn’t recommended by dentists.
Keep Your Most Recent Set
The one set worth saving is the tray you just finished wearing. If your current aligner cracks, gets lost while traveling, or your retainer breaks after treatment ends, that previous set can act as a temporary stand-in to keep your teeth from shifting while you get a replacement. This is a short-term fix, not a long-term solution, since an older tray won’t match your current tooth positions precisely. But it’s far better than going without anything.
If you’re storing a set for backup, clean it first. A 20-minute soak in a 3:1 mix of distilled white vinegar and water works well. You can also use equal parts hydrogen peroxide and water for 30 minutes, or a tablespoon of baking soda in half a cup of water for about an hour if there’s visible staining. After soaking, rinse with water, let it dry completely, and store it in its original case in a cool spot. Keeping it sealed in the case limits air exposure and prevents bacteria from building up.
Avoid storing trays anywhere warm. Heat warps the plastic and ruins the fit, which defeats the entire purpose of keeping them.
Why You Can’t Recycle Them Curbside
An estimated 25 million dental aligners end up in landfills every year. The reason they can’t go in your regular recycling is their multi-layered plastic composition. Curbside recycling facilities aren’t equipped to process that type of material, so tossing them in the blue bin just contaminates the recycling stream.
In the U.S., there’s an additional wrinkle: used aligners may be classified as contaminated medical waste since they’ve been in prolonged contact with saliva. That classification makes them ineligible for routine recycling in some jurisdictions.
Specialized programs do exist. Angel Aligner partnered with TerraCycle to launch a recycling program using TerraCycle’s Zero Waste Box system, which collects, transports, and processes hard-to-recycle dental plastics. Your orthodontist’s office may participate in a similar program. It’s worth asking at your next appointment whether they collect old trays for recycling, since sending a box through an individual patient is less practical than a dental office collecting trays in bulk.
Don’t Use Them as Whitening Trays
This is one of the most common ideas people have for old aligners, and dentists consistently advise against it. Invisalign trays weren’t designed to hold whitening gel against your teeth. The aligner edge usually ends before the gumline, and the rigid plastic doesn’t create a tight seal the way a custom whitening tray does.
That poor seal causes two problems. Whitening gel leaks out of the tray and onto your gums, which can cause burning and irritation. At the same time, saliva seeps in and dilutes the bleaching agent, breaking down its active ingredient quickly. The result is uneven whitening at best and gum irritation at worst. If you want to whiten your teeth, a custom-fitted whitening tray from your dentist will give you dramatically better results.
What to Do With the Rest
For every set besides your most recent one, the realistic answer is the trash. There’s no practical home use for old aligners. They’re molded to a specific stage of your tooth movement, so they won’t fit properly on anyone else’s teeth. Craft projects or keychains made from old trays are occasionally suggested online, but the material is difficult to cut or reshape safely, and most people find it’s not worth the effort.
If throwing them away bothers you from an environmental standpoint, the most impactful step is asking your orthodontist whether their office participates in any aligner recycling program. Some offices collect used trays from multiple patients and send them to specialized recyclers in bulk. Even if your provider doesn’t offer this yet, patient interest can push practices to adopt these programs.
For the trays you do discard, bag them separately rather than mixing them into general recycling. Since they’ve been in contact with your mouth for extended periods, treating them as non-recyclable waste keeps the recycling stream clean and avoids potential contamination issues at processing facilities.