Custom oral appliances are made from standard dental acrylics and plastic and occasionally contain metal parts to them. Most dental devices are made from hard acrylic. Some have a softer inside liner that touches your teeth. This makes for a more comfortable fit. If you have very short straight teeth, then we may recommend that you’re dental device be lined with a thermoplastic material called ThermAcryl. This allows us to simply reheat your device with hot water–refit it after maybe you’ve had a crown or bridge done by your dentist. You should never attempt to reheat and refit your dental device yourself.