Full dentures are used if there are not any teeth left for support. The full denture covers more of the jaw than a partial denture and is partly held in place by a natural vacuum in the mouth.
With new advances in implant dentistry, dentures can be made to lock into your mouth. This provides you the ability to chew and eat things your old dentures may not have allowed you to. With as few as two implants, a lower denture can go from a wobbly mess to a stable set of teeth.