Dental plaque which is always present in the mouth until removed, contains bacteria that turns the sugar that is ingested into acid which then attacks the teeth causing decay. Without sufficient saliva the sugar converts faster and plaque hardens more quickly causing even more damage to dentition. Dry mouth can also lead to a propensity for gum disease. As the gums shrink and tooth roots are exposed, tooth decay becomes more likely.
Dentures wearers can be affected by both the lack of saliva causing dentures to lack sufficient suction, becoming too loosely fitted and causing blisters and ulcers from rubbing on the gums.