Many individuals rely on stock mouthguards made from thermoplastic material for athletic activities or to protect against nocturnal teeth grinding. These “boil-and-bite” devices often require multiple attempts because the initial fitting may not yield an ideal impression of the teeth and gums. A poorly fitted guard may shift during use or fail to offer adequate shock absorption. Fortunately, the thermoplastic polymer allows the material to be softened and reshaped multiple times to achieve a secure, comfortable fit.
Confirming Your Mouthguard Type and Gathering Supplies
This technique is intended for thermoplastic or ethylene-vinyl acetate (EVA) devices, commonly known as the boil-and-bite type. Confirm your guard is not a hard acrylic or a custom-fabricated appliance, as those materials cannot be safely altered using heat at home. Heating a hard acrylic guard will likely cause it to crack or warp permanently.
Before beginning, gather a few basic items. You will need a small pot, a stove or heat source, and enough water to completely submerge the mouthguard. A slotted spoon is necessary for safely handling the heated guard, along with a timer and a mirror to check the molding process.
The Step-by-Step Remolding Procedure
The process begins by bringing the water to a temperature just below boiling, typically between 150°F and 170°F, which is sufficient to soften the thermoplastic without causing permanent damage. Once the water is heated, carefully place the mouthguard into the hot water using the slotted spoon, ensuring it does not rest against the bottom of the pot. Allow the mouthguard to remain submerged for the manufacturer’s specified time, generally between 30 and 60 seconds.
Next, remove the guard from the hot water and immediately dip it into a bowl of cool or lukewarm water for approximately one to two seconds. This brief cooling period is crucial for dropping the surface temperature to prevent burning sensitive tissues inside the mouth. It also stops the softening process from progressing further. The guard should feel warm and soft but not floppy or excessively hot when touched.
Once the guard is safe to handle, quickly place it over your upper teeth, ensuring it is centered on the dental arch. Gently bite down on the guard to begin the impression process, maintaining a firm pressure. While biting, use your fingers to press the material firmly up against the sides of the teeth and gums, starting from the back molars and moving toward the front. This action eliminates air pockets and ensures the plastic conforms tightly to the unique contours of your mouth.
Simultaneously, apply suction by closing your lips and gently sucking the air and water out from between the guard and your teeth. Use your tongue to press against the inside surface of the guard, further encouraging a tight fit along the palate. Hold this position for at least 30 seconds to one minute, giving the thermoplastic time to begin cooling and hardening. Finally, remove the mouthguard and place it into cold tap water or ice water for several minutes to complete the hardening process and fully set the custom shape.
Fine-Tuning the Fit and Troubleshooting
After the mouthguard has cooled and hardened, insert it to check for proper retention and comfort. A well-fitted guard should remain securely in place on the upper teeth without needing to be held by the jaw, even when you open your mouth or speak. If the guard feels too bulky or irritates the soft tissue near the last molar, you may carefully trim the excess material using sharp scissors. Trim small amounts at a time, smoothing the cut edges with a brief dip back into the hot water if the plastic feels abrasive.
If the mouthguard feels loose, shifts easily, or the impression is not deep enough, the entire remolding process should be repeated. Thermoplastic materials can withstand being reheated and reshaped three or four times before showing signs of degradation. Strictly adhere to the recommended heating times and temperatures during subsequent attempts. Overheating the material can cause the polymer to break down, resulting in a brittle, porous, or permanently distorted guard that will no longer provide sufficient protection.