What causes xerostomia?

Any alteration in the quantity or quality of one's saliva will reduce those benefits that saliva can provide. The presence of xerostomia, which refers to a state of diminished salivary flow, can tip the balance between tooth demineralization and remineralization in favor of tooth decay formation. Possibly you have noticed that when you first wake your mouth seems dry and stale. This is because when we sleep our body curtails the amount of saliva that our salivary glands produce. Beyond this nocturnal mouth dryness, some people will notice that their mouth is chronically dry. This may be related to a person's age. With increasing age our salivary glands tend to work less effectively, and the composition of our saliva can change also. Either of these factors can lessen the preventive benefits of saliva and put us more at risk for tooth decay. Xerostomia can also be a side effect of the medication a person is taking.