The primary cause of bad breath is poor oral hygiene. Bacteria from food debris that remain on or in between the teeth can become rotten; producing sulfuric compounds that cause an unpleasant odor.
Smoking can also contribute to bad breath. Tar and nicotine residues from cigarettes bind to the teeth, gums and sides of the cheeks. Diet can also have an impact on producing bad breath.
In addition, braces can contribute to bad breath due to the increase in plaque accumulation.