A conventional denture replaces a full arch of teeth and is made after all teeth have been extracted and the tissues (gums) have healed. Palatal coverage with acrylic is a necessity in order to create a vacuum. This is the retentive mechanism of a conventional denture. Depending on the ridge form and remaining bone or soft tissue, a denture can be retentive and stable or retentive and not stable (no bone remaining). A lower denture is very dependent on retention based on the ridge form. There is little or no vacuum created on the lower arch with a denture and many patients suffer tremendously due to the movement of the denture.