From the mouths of experts
The dentists say bad breath is caused by dental problems, this is perhaps the most common cause of bad breath. It is in the mouth and specifically in the teeth, where food is hidden, it remains, causing the horrible decay give way to the stench. Plus it makes the area become infectious, so we recommend that a good hygiene.
The gums are also causing oral malodor, because getting a virus and inflamed, causing bad breath. A misplaced tooth (amalgam, bridges, or dentures) or until they are absent can also be a source of an unpleasant odor in the mouth.
It is therefore important that you go to the dentist regularly, and clear brush your teeth every day.
