Vertical wrinkles around the mouth may be caused by ill-fitting dentures. False teeth that may once have fit well, change considerably as time goes by. When no teeth are present, the gum and bone tissue become unnecessary and nature removes them. They shrink upward,therefore causing the cheek to sag. Wrinkling and gauntness in the face are two things you must deal with as you grow older, but old or ill‑fitting dentures can be responsible for some of these lines.