dentalA denture is a prosthesis which is made to replace teeth and gums which have been lost due to caries( decay) , periodontal( gum) desease and injury.
It is made up of 2 components: the teeth which replace your missing teeth, and the pink acrylic or plastic to replace the gum you have lost. They are not permanently fixed in the mouth and have to be removed daily for cleaning.When we lose teeth, we also lose the bone which surrounded those teeth. Initially this loss happens fast and aggressively, but then slows down and continues slowly through the years. This bone and tooth loss causes the face to collapse inwards since there is decreased support for the facial muscles.
By replacing the missing teeth, we are restoring aesthetics, speech, function( eating) and as stated already, support to the face muscles. 

Dentures can be complete, when you have lost all your teeth, or partial, when you have lost some of your teeth. In turn, the frame of the denture( what holds the false teeth in place) can be plastic or metal( chrome- cobalt). The advantage of the metal frame is that it is less bulky , much thinner and much stronger than plastic. Hence it is a better choice to the plastic dentures.

Dentures can also be classified as conventional or immediate- conventional meaning that they are done after 2-3 months that the patient has had the teeth removed and the gum has healed. Hence the patient must wait for some time without teeth. Immediate meaning that the denture is inserted immediately after the teeth are extracted so as not to spend time without teeth. In this case since the gum will change shape with time, the immediate denture will need to be adjusted after a while.
All dentures will need to be adjusted/ replaced after some years since the gum continues to alter as time passes.

Having false teeth does not mean that the mouth should not be looked after. The palate and the tongue should be regularly brushed, as also the gums. Regular dental checkups should be made to see that there is no pathology in the oral tissues.
The dentures themselves should be washed daily and kept very clean. Your dentist will explain to you the best materials to use to keep them clean and looking as new as possible.

Sometimes if the gum has altered and shrunk too much, dentures become a problem because they become very unstable in the mouth. In this case there is the option of doing implant supported dentures. See implants/ your dentist will explain further.

dentures

dentures

dentures