Dr. Greene’s Answer:
In children, smelly breath that persists throughout the day is most often the result of mouth-breathing, which dries out the mouth and allows the bacteria to grow. Children who consistently breathe through their mouths might have colds, sinus infections, allergies, or enlarged tonsils or adenoids blocking the nasal passages, so a visit to the pediatrician is in order. Thumbsucking or sucking on a blanket can also dry out the mouth.
To improve most cases of bad breath, the goal is to decrease mouth bacteria and increase saliva. The better your daughter’s toothbrushing technique, the smaller number of bacteria will be present. Make after-meal brushing a habit. Use a timer to help her brush for at least two minutes. Be sure she brushes her tongue. You might also try a rotary electric toothbrush. I do not recommend mouthwashes or fluoride rinses in very young children who tend to swallow them. Breath mints may mask the problem, but don’t get at the source. As your daughter gets older, sugarless sour candy or sugarless chewing gum can get the saliva flowing and get those mouth muscles moving.
The American Dental Association (ADA) also recommends flossing at least once a day and increasing fluid intake (http://www.ada.org/). Recent studies involving adult subjects suggest that commercially available tongue scrapers/cleaners may be slightly more effective than using a toothbrush to clean the tongue (J Am Dent Assoc, 2001 Sept., Vol 132, No 9, 1263-1267; Gen Dent. 2006 Sep-Oct;54(5):352-9; 360, 367-8). However, studies using tongue scrapers/cleaners still need to be performed in children.
If the problem persists, she should see her doctor. Bad breath in children that doesn’t respond to the above measures should be investigated.