Dry mouth is a subjective feeling, not a distinct disease. Xerostomia is not a
synonym for hyposalivation since it may also occur with the changes in the quality
of saliva, while the amount of saliva stay unchanged. This is the reason that people
sometimes complain of dry mouth but have proper salivation . Therefore, a patient
complaining of dry mouth cannot automatically be assumed to have salivary
dysfunction, while oral dryness may have many causes . Any individual may
experience xerostomia with or without hyposalivation, experience hyposalivation
with or without xerostomia or may have an average salivary flow and normal sensation