If bad breath is caused by something you ate, chewing sugar-free gum can help. Gum can remove food and bacteria that are related to oral odors. However, if bad breath returns often after chewing gum, you may need to consult a doctor. Bad breath that returns or lingers can indicate a more severe condition, like periodontal disease or cavities. If bad breath is caused by something you ate, chewing sugar-free gum can help. Gum can remove food and bacteria that are related to oral odors. However, if bad breath returns often after chewing gum, you may need to consult a doctor. Bad breath that returns or lingers can indicate a more severe condition, like periodontal disease or cavities.