If you maintain good oral hygiene and don't have specific oral problems, your bad breath may be caused by other medical issues. In that case, you are strongly advised to see a dentist to find out the cause and receive appropriate treatment.
Poor Dental Hygiene
Respiratory Tract Infections
Dry Mouth (Xerostomia)
Infections in the Mouth
External Agents
Systemic Illnesses
85% of bad breath symptoms are linked to oral hygiene issues.