Sometimes the original impression can look great but has a small defect that is not really visible, it's only when the night guard is worn that a distortion or defect becomes apparent by causing pressure or sore spot.A quick home fix you can try : Boil some water and carefully pour it over the offending sedge of the night guard, take care not to scald your fingers, the hot water will soften the area very quickly 5-10 seconds. Gently shake off the excess hot water, bend the edge slightly with your fingers then quickly place it back into your mouth. The softened plastic should then adapt to the shape of the area without causing undue pressure. A few sips of some cold water will help cool and fix the new shape/position. You can repeat this as many times as you like to get the area comfortable.The second alternative is to mark the area in question and send it back to us and we will ease the area for you.