are mostly very durable, but they are not indestructible and no more permanent than eyeglasses
. Even though meticulous care will extend their life and maintain their appearance, over time dentures will need to be relined, rebased, or remade due to normal wear. Dentures may need to be replaced if they become loose and the teeth show signs of significant wear. Loose dentures are the result of a mouth naturally changes with age. Bone and gum ridges can recede or shrink, causing jaws to align differently and dentures to fit less securely. Poorly-fitting dentures can cause sore spots from the rubbing of the acrylic against the gums, and may become infected, which if left untreated, could develop into oral cancer. You should have your father scheduled for an appointment with a dentist
at least once a year to screen for oral cancer. The dentist can determine whether or not his dentures need to be replaced at that time. On average, most dentures are replaced between 3-8 years combined with a number of factors such as wear and deterioration of the denture materials and changes that occur in the denture wearer's jaw. I strongly advise your father to see a dentist soon.