There are many causes of xerostomia or “dry mouth” and depending of these causes we can talk of differents types of xerostomia.
Xerostomia can be total or partial depending on the quantity of saliva and irreversible or reversible when the salivary glands can or cannot recover their normal function.
Total or partial xerostomia
Xerostomia is total when there isn´t saliva at all.
Xerostomia is partial when the salivary production has decreased but it hasn’t disappeared completely.
The level of oral dryness varies depending on the number and the importance of salivary glands affected.
If only a few glands are affected, the rest will continue operating properly. It would be the case of a stone or calculi (sialolith) inside the salivary duct, that it would only affect the gland with the stone. The rest of the glands will continue secreting saliva normally.
On the other hand, depending on the importance of the gland affected the decrease of saliva may be higher or lower. If a major salivary gland (the glands that make more saliva) is affected, the person will note more dryness in his mouth.
Below you will find a detailed explanation of the types of salivary glands and how they work.
Reversible or irreversible xerostomia
Xerostomia may be total or partial and also reversible or irreversible.
Reversible or temporary xerostomia
Dry mouth may be temporarily caused by medications or infections that alter the glandular function. However, the salivary glands keep some residual activity and when the problem finishes, the salivary glands recover their normal function.
Irreversible or permanent xerostomia
In cases of permanent dry mouth there is an irreparable damage to the salivary glands due to autoimmune diseases (as Diabetes or Sjögren’s syndrome) or patients receiving large doses of radiation as treatment to neck or head cancer. In these cases, the salivary glands cannot recover their normal function because there is a permanent damage to their essential or functional elements like glandular tissues (fibrosis) or cells.