Fact - While it is true that well fitting dentures are used by the patient for many years, it is a myth that it can be retained forever. The oral tissues that lie below the dentures change over a period of time. But the dentures are made of stiff materials that do not adapt according to the changing contours of the oral tissues. Thus even a well fitting denture may not fit well after a few years. If an ill-fitting denture is continued to be worn, it can cause damage to the underlying tissues. Thus most dentists advice changing of the dentures once in at least 5 years.