Saliva flow helps minimize bacterial growth, he said. Saliva works like an oral water fountain, bathing all the tissues in the mouth and washing away food particles, said Alabama-based dentist Paul Bussman, spokesman for the Academy of General Dentistry.
Some medications, salivary gland problems, or continuously breathing through the mouth can impede saliva flow, according to information from the American Dental Association at www.ada.org on the Web. Fasting also can trigger bad breath because infrequent eating inhibits saliva flow, Bussman said.
Gum disease and such dental problems as poor or old bridge work - under which food and bacteria can lodge - also can cause halitosis, he said.
Such edibles as onions, garlic and coffee can continue contributing to bad breath until the body eliminates the food, according to the ADA. The food is absorbed into the bloodstream, then transferred to the lungs, where it is expelled. Strong foodstuffs might be detected on a person's breath for up to 72 hours after digestion. Studies have shown that even garlic rubbed on the soles of the feet can show up on the breath, the ADA Web site states.
"It literally is bad breath," McAllister said.
Giving bad breath the brushoff
Dentists' best advice for preventing bad breath? Brush everything, go to the dentist, and use a tongue scraper.
Most bacteria start on the back side of the tongue as it nears the throat, so good tongue hygiene is crucial to stemming bad breath, Bussman and McAllister said.
"Your tongue's covered with bacteria and its byproducts - the bacterial poop," McAllister said.
He and Bussman recommended using a tongue scraper, a plastic tool that scrapes away bacteria that builds on the tongue. The tool isn't as likely as a toothbrush to gag users as they scrape their tongues' far regions, Bussman said.
The Academy of General Dentistry also suggests brushing the cheeks and the roof of the mouth.
Toothbrushes should be replaced at least every six months or when the bristles become frayed or otherwise worn, and immediately after a cold or illness, Bussman said. Always use a soft toothbrush, running the bristles under warm water to soften them even more before brushing gums, he added.
Dispelling the mouthwash myth
Most mouthwash products will not eliminate halitosis - and some can contribute to the problem, dentists said.
"It's mostly a cover-up and a temporary fix," McAllister said. "It is a fresher taste, but it's a temporary freshness."
Mouthwash that contains alcohol can sap saliva, he said.
Sugar-free gum, on the other hand, can stimulate saliva flow. Bussman said gum with xylitol, a sweetening ingredient that inhibits bacterial growth, can be especially helpful for curbing halitosis.
Individuals plagued with bad breath despite practicing good dental hygiene might be suffering from a medical disorder that's causing halitosis, McAllister said. The American Dental Association states that halitosis can be a sign of respiratory tract infection, sinusitis, postnasal drip, chronic bronchitis, diabetes, gastrointestinal disturbance or problems with the liver or kidneys. Odor originating from the back of your tongue might indicate postnasal drip - mucus secretion from the nose moving down the throat and getting stuck on the tongue, according to the Academy of General Dentistry.
Contrary to popular belief, halitosis rarely originates in the stomach, Bussman said.
The American Dental Association advises individuals with chronic halitosis despite good oral hygiene to discuss medical concerns with their dentist, keep a log of the foods they eat and make a list of medications they take. This information can help the dentist pinpoint the cause of bad breath.