You can remold a boil-and-bite mouthguard by softening it in hot water for about 20 seconds, then pressing it against your teeth to create a fresh impression. Most guards can handle two to four remolding cycles before the material degrades too much to hold a clean shape. The process takes under five minutes and uses the same technique you’d follow when molding a new guard for the first time.
What You’ll Need
Gather these before you start: a pot or bowl deep enough to fully submerge the mouthguard, a large spoon or tongs, a separate container of cold water, a clean towel, and a pair of sturdy scissors if you need to trim any edges afterward. That’s it. No special tools required.
Step-by-Step Remolding Process
Bring water to a boil on the stove, in a kettle, or in the microwave. Pour it into a bowl or leave it in the pot, making sure there’s enough depth to cover the entire mouthguard. Drop the guard gently into the water and let it soften for around 20 seconds. Don’t leave it in longer than that. Overheating the material can cause it to warp or become too thin to remold properly.
Use a spoon to lift the guard out carefully. Watch that the sides don’t fold over and stick to each other while it’s soft. Dip it into the cold water for no more than two seconds, just enough to make it safe to handle, then blot it quickly with the towel and get it into your mouth right away. Speed matters here because the material starts firming up almost immediately.
Center it against your upper teeth. Use your thumbs to push the guard up and back against your molars first, then press it around your front teeth. Bite down firmly so your lower teeth leave a clear impression on the underside. Press your tongue against the roof of your mouth to create suction and hold the guard tight against your upper teeth. Hold everything in place for 30 to 45 seconds. Don’t chew on it or shift it around during this time.
Once the guard has set, remove it and check the fit. If it still feels loose or uncomfortable, you can repeat the entire process. Most people get a good fit on the first or second attempt.
How to Tell if the Fit Is Right
A properly molded mouthguard stays in place on its own without you clenching your jaw to hold it. It should cover all of your upper teeth and sit snugly enough that it doesn’t shift or fall out when you open your mouth. You should be able to breathe and talk reasonably well, even if your speech sounds slightly muffled.
If the guard pops loose when you open wide, slides forward off your molars, or presses painfully into your gums, the mold isn’t right. Try again. You can also trim areas that extend too far into your gums or the back of your mouth using sharp scissors or a razor blade after the guard has cooled completely.
How Many Times You Can Remold
Most boil-and-bite guards hold up for two to four remolding cycles. After that, the thermoplastic material loses its ability to take a clean impression. Higher-quality guards, especially thicker dual-layer models with a soft inner layer and a harder outer shell, typically handle three to four cycles without noticeable degradation. Thinner, single-layer guards may only give you one or two good remolds before they start feeling flimsy.
Each time you reheat the material, it gets a little softer and a little thinner in the spots where your teeth press hardest. If you notice the walls of the guard becoming noticeably thinner after a remold, or if it no longer holds its shape well, it’s time for a new one rather than another round of reheating.
Which Mouthguards Can Be Remolded
Boil-and-bite mouthguards are designed to be remolded. They’re made from a thermoplastic material that softens predictably in hot water and firms up again at mouth temperature. These are the guards you find at most sporting goods stores, and they’re built to be reshaped.
Custom mouthguards made by a dentist are a different story. They’re fabricated from a more durable thermoplastic that’s molded using a precise dental impression, and they’re not meant to be reheated at home. Attempting to boil a custom guard will likely ruin it. Stock mouthguards, the generic one-size-fits-all type, can’t be remolded either because they aren’t made from heat-moldable material in the first place.
Remolding With Braces
If you wear braces, your teeth are constantly shifting, which means a mouthguard that fit well a month ago may feel loose or uncomfortable now. Remolding more frequently is expected. The process is the same: soften in hot water, press against your teeth, and bite down.
The important difference is the type of guard you use. A standard boil-and-bite mouthguard doesn’t have enough room to fit around brackets and wires, and it won’t protect them properly. Look for guards specifically designed for orthodontic use, which have extra space built in to accommodate the hardware. Some cheaper guards are only designed for a single mold and should be replaced rather than remolded once they stop fitting. If you’re going through braces treatment, expect to remold or replace your guard every few months as your teeth move into new positions.
When to Replace Instead of Remold
Remolding can fix a loose fit, but it can’t fix structural damage. Replace your mouthguard if you notice any cracks, holes, or areas where the material has worn visibly thinner. A guard that’s been bitten through in spots or has started fraying at the edges has lost its ability to absorb impact, and no amount of reheating will restore that protection.
Other signs it’s time for a new guard: it causes jaw or tooth pain that wasn’t there before, it no longer stays in place even after a fresh remold, or it’s been through the maximum number of reheating cycles and still doesn’t fit well. Natural tooth movement, dental work, or even weight changes can alter your bite enough that the old guard simply can’t conform anymore. At that point, a fresh guard will give you a much better result than trying to squeeze one more cycle out of worn material.