The tonsils cause about 3% of bad breath.
The tonsils are actually part of your immune system. They have tiny little holes on their surface. Occasionally, bacteria live in these holes, and then get killed by your immune system. These conglomerations of dead bacteria and dead immune system cells are usually squirted out of the little holes, and then you swallow and eat them.
But sometimes, instead of being squirted out, they stay and calcify. They get turned into tonsilloliths (meaning "tonsil stones") that are about half the size of a head of a match - and smell quite nasty. They cause no other medical problems, (besides bad breath) and so many doctors and dentists have not heard of them.
In 5-10% of cases, bad breath happens in the nose - from sinusitis, or a reduced mucus flow, or rarely, a foreign body.
There was the curious case of a 28-year-old woman who went to her doctor complaining of persistent bad breath. When he looked up her nose, he found a small bead that she put up there as a young child. When he removed the foreign body, the bad breath vanished - after quarter of a century.
But in the vast majority of cases, 85-90%, bad breath is generated in the mouth - and practically all of it comes from the back of your tongue. (A small percentage of mouth-generated bad breath does come from diseased teeth or gums. A famous encyclopaedia wrongly claims that bad breath "... is due to the rotting debris in the pockets under the gum margins").
The tongue is triply famous. First, it's the only muscle in your body that gets stronger with age. Second, it's probably the muscle that's the most fun to exercise. And third, the tongue is like a shag pile carpet. The bacteria responsible for bad breath live in tiny holes on the shag-pile surface of your tongue.
But how can you tell if your breath stinks?
Luckily, in 1995, Mel Rosenberg looked at (and solved) this problem when he ran an "Oral Malodor Clinic" in Tel-Aviv. He set up a study to see if people were "able to smell their own malodor". Mel worked with 52 Israeli citizens, 43 of whom claimed that they had bad breath.
He had them run through the "well-tried-and-maybe-true" techniques for inhaling and checking your own bad breath. He got them to cup their hands over their mouth and nose, and then breathe out through the mouth and in through the nose. He also got them to do the breathe-rebreathe thing under the blankets, as well as smelling their freshly-used telephone mouth piece and their freshly-used piece of dental floss. He even got them licking their wrist "in a perpendicular fashion", and then sniffing it.
He then added his own brand-new technique. They were to spit into a laboratory dish that was then closed and cooked at 37°C for 5 minutes, and finally "presented for odour assessment" to the spitter.
Of course, Dr. Rosenberg would be the impartial "odour judge". This meant that he had to sniff 52 mouths breathing upon him, 52 saliva-covered wrists, 52 telephone mouth pieces, 52 strands of dental floss, and 52 warmed-up samples of saliva in a laboratory dish. To make sure that his nose didn't get overloaded and stop functioning normally, he would regularly sniff his control solution - "chicken-dung based fertiliser in aqueous suspension ... in an opaque sniff bottle."
He found that there is no simple way to accurately know if you have bad breath. There was absolutely no relationship between how the volunteers, and Rosenberg, rated people's breath odour.
The only case where there was any reliability was with his special "incubated spit technique". It's not simple, but you can monitor your own breath status. Unfortunately, you have to go to the trouble of carrying around a sealable laboratory dish, and "cooking it" in your armpit or next to your body for 5 minutes.
But Mel Rosenberg also offered seven tips for good breath in his Scientific American article of April, 2002.
1. Clean the back of your tongue with a scraper or a toothbrush;
2. Eat breakfast - it gets the saliva flowing and cleans the mouth;
3. Stop your mouth from drying out by chewing gum or drinking water;
4. Rinse and gargle with a mouthwash just before sleep. This slows the growth of bacteria overnight;
5. Clean your mouth after you eat/drink smelly foods/drinks such as garlic, curry or coffee. If you eat or drink foods high in proteins, clean between your teeth;
6. Of course, always floss and brush;
7. The most reliable way to check for bad breath is ask a family member to smell you.
That, or any of the above, is vastly preferable to spending the day anxiously spitting in a dish, or licking your wrist.http://www.oraltech.com.au