If the mouthguard is soft enough, you may be able to bite down on the guard to give you a guide on where your teeth sit in the mouthguard. You can use this to help trim the mouthguard down. Don’t worry if the mouthguard doesn’t fit perfectly over your teeth. It just needs to fit comfortably in your mouth at this point.
If you bit into the mouthguard and can see the impression of your teeth in it, trim the mouthguard so that it just covers your teeth. Any part of the mouthguard near the back that does not have a bite mark on it can usually be removed.
Don’t worry if the cut is a little jagged, or if it feels strange against the back of your mouth at this point. Boiling the mouthguard in water to mold it will also help soften any rough edges. The mouthguard should only just cover your second molars when it’s at its perfect length. [4] X Research source
Make sure there is enough water in the pot to fully submerge your mouthguard in. If you don’t have access to a stovetop or something similar, you can use a microwave to boil the water. Microwave the water in a microwave safe bowl for 4 to 5 minutes, or until the water begins to boil.
If you’re using a mouthguard designed for playing American Football or something similar, you can use the strap on the front of the guard to hold the mouthguard in the water. Always follow the manufacturer’s instructions when boiling your mouthguard. Most will require that they’re boiled for around 30 seconds, but some may take more or less time.
Avoid moving the mouthguard around too much, as you may mold it too much while it’s still hot. You can also dip the mouthguard into cold water for 1 second to cool it off and wash away any boiling water.
Once you put the mouthguard in your mouth, you’ll only have around 30 seconds before it becomes too cool to easily mold. Work quickly to shape it to each of your teeth.
If the mouthguard isn’t quite right, you can repeat the process of boiling and molding it to reshape your mouthguard again.
