Odor-producing bacteria that grow in the mouth cause bad breath. When you don’t brush and floss regularly, bacteria accumulate on the bits of food left in your mouth and between your teeth. The sulfur compounds released by these bacteria make your breath smell bad. If you brush and floss properly, but your bad breath persists, you may have a medical problem like Sinusitis or Periodontal (Gum) Disease. Call your physician or dentist if you suspect such a problem. Learn more about Periodontal Disease by clicking here.