Bad breath also known as halitosis is a serious concern that can lead to social isolation and embarrassment. 

There are two kinds of bad breath: real and delusional. 

Delusional halitosis can occur when a patient complains of a bad odor which other people can not smell. Halitophobia is when a patient fears he has bad breath and that his bad breath will not go away in spite of treatment. Both these conditions require counselling to resolve.

Real halitosis is actual bad breath and it can originate from causes inside the mouth or outside the mouth: 

Bad breath from causes inside the mouth: 

This accounts for about 85% of cases of bad breath.  The main causes of bad breath that comes from the mouth are gum disease, infections around wisdom teeth, bone infections, and dry mouth.  Poorly fitting bridges or dentures or big spaces between the teeth where food gets stuck can also cause bad breath. Yeast overgrowth in the mouth is another cause bad breath, Other diseases that can cause growths in the mouth such as tuberculosis or syphilis can be a cause of bad breath, although this is quite rare.

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