Upper dentures are supposed to fit snugly to the roof of your mouth without feeling tight. Lower dentures feel much looser as they simply rest on the ridge of your jaw and rely on gravity to keep them in place. If an upper or lower denture regularly shifts out of place or pinches or chafes your gums, then that’s a sign you need to have something adjusted. Dental implants can help your denture to stay in place, especially for lower dentures.