Features indicating halitosis is arising from within the mouth:
(1) The offensive odor arises from the mouth and not from the nose. This can be screened for by comparing odor during mouth and nasal breathing. For testing nasal breathing it may be necessary to use a mouthpiece with tubing that exits remotely from the observer.
(2) The odor gets worse if:
(2a) the person starts talking.
(2b) the mouth dries out
(3) The odor gets better following:
(3a) use of a strong mouthwash for a week or more.
(3b) proper oral hygiene, with deep tongue brushing, especially of the posterior tongue
For the change with oral care or mouthwash use it is important to be sure that the patient is compliant.
Readily modifiable forms of oral halitosis:
(1) dietary (garlic, onions, soft cheeses, fermented fish, fermented cabbage, etc.)
(2) tobacco smoking
(3) somewhat poor dental hygiene
Differential diagnosis of oral halitosis:
(1) nasal halitosis
(2) metabolic disorder (uncontrolled diabetes, hepatic or renal failure, hereditary metabolic disorder)
(3) cancer
(4) other sources
