Congratulations! You’ve just undertaken an orthodontic treatment! Even though retainers are smaller than in previous generation, you may feel some pain in your cheeks. Feel free to apply orthodontic wax contained in your pouch onto the retainer bothering your until it is fully healed or until you feel comfortable. You can also rinse out your mouth with salty water (8 ounces of water and ½ teaspoon of salt) to aid in healing.
With regard to Invisalign shells, wounds are rare, but may be present depending on the position of your teeth and the shells placed on top of them. If you feel discomfort, apply orthodontic wax wherever you feel the injury.