Science Fair Project Encyclopedia
Halitosis, breath odour, or most commonly bad breath are terms used to describe noticeably unpleasant odours exhaled in breathing. Though specific odours can be caused by sometimes serious medical conditions, bad breath is typically innocuous in itself, and only causes problems in interpersonal relations (one's own breath odour is usually undetectable due to the process of habituation). Whereas odours indicating underlying pathology can stem in the stomach, lungs, or bloodstream, most bad breath arises in the mouth and upper throat.
Though the causes of breath odour are not well understood, the most unpleasant odours are thought to arise from food trapped in the mouth which is processed by normal mouth flora. Large quantities of bacteria are often found on the back of the tongue, in the throat rather than in the mouth, where they are undisturbed by normal activity; they build up to the point where their metabolism is largely anaerobic. The anaerobic respiration of such bacteria can yield either a putrescent smell, or that of sulfur compounds such as hydrogen sulfide and thiols.
Other causes include the well-known effects of ingesting onions, garlic, or other such foods; these result in a more systemic order, and are harder to treat without ending the consumption of the foods; however they do resolve themselves relatively quickly when the food is not consumed. Consumption of coffee is an intermediate cause, giving a slight systemic odor but also greatly increasing the odoriforous bacterial buildup.
An easy way to determine bad breath is licking the back of the hand, let saliva dry and sniff it. Another way would be to scrape the posterior of the tongue with an inverted spoon, and to sniff the contents of the spoon. Please see the external link to Animated-Teeth.com below for more details.
Brushing teeth and using breath-freshening mouthwash or lozenges gives only temporary relief at best, since the problem is usually further down the truth, not in the mouth.
Bad breath can be reduced by using hydrogen peroxide, combined with yoghurt containing active bacterial culture. Hydrogen peroxide at a concentration of 1.5% can be taken as an oral antiseptic by gargling 10 ml, about two teaspoons. Hydrogen peroxide is commonly available at a concentration of 3% and should be diluted to 1.5% by mixing it with an equal volume of water. Hydrogen peroxide is a powerful oxidizer which kills most bacteria, including useful aerobic bacteria. Unless yoghurt is eaten or aerobic bacteria is added by some other means, foul smelling bacteria will eventually reproduce, so on its own the effects of hydrogen peroxide are temporary. Yoghurt with active bacterial culture contains beneficial aerobic bacteria, which does not have a bad odor. This bacteria helps digestion and by occupying the host, prevents other bacteria from returning. So eating yoghurt colonizes the host with good bacteria, especially after most of the previous bacteria were killed by hydrogen peroxide. This combination displaces odor causing bacteria for a long time.
Temporary relief for a number of hours can often be gained by scraping as much of the bacterial mass from the back of the tongue as possible. Specific products are sold for this purpose, but an inverted teaspoon will also do a creditable job. Merely brushing the back of the tongue with a toothbrush will not work, however, as the head of a toothbrush is usually too large to reach down where the bulk of the bacteria are located. Often when a toothbrush fails to resolve the problem, more effective means of scraping the tongue are not attempted, even though they would be of value.
Since dry mouth can increase bacterial buildup and cause bad breath, chewing sugarless gum can help with the production of saliva, and cut down on bad breath. Sometimes, bad breath is caused by stomach odors, so watching the foods you ingest may help.
Another way to reduce bad breath is through products (e.g., toothpastes and oral rinses) which contain oxygen or chlorine based oxidizing agents which act as a natural weapon against anaerobic bacteria, temporarily. TheraBreath products, for example, contain such oxidizing agents.
Many stores also carry tongue scrapers, which can be used to clean the posterior of the tongue (see "Home Care").
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