Gas 1 - Rotten Eggs
comes from the gas Hydrogen Sulphide, which comes from the amino acid Cysteine. Bacteria that break this amino acid down usually live on the tongue, in the depths of the tongue papillae. When I use my Halicheck Gas Chromograph, I use the level of this gas as my indicator of how well you clean your mouth in general. A high reading means to me that you are leaving bacteria rich biofilm in the mouth due to either haphazard cleaning or infrequent cleaning. I rarely see high levels of this gas in chronic halitosis sufferers as they are fastidious mouth cleaners.
Gas 2 - "Poo Breath" or Faeces
This gas comes from Methyl Mercaptan, which comes from the amino acid Methionine. Bacteria that break this amino acid down can either live at the gag reflex or under the gums. So levels of this gas are extremely important. I use it to measure the level of mouth health. A low level usually means that you have protein rich coating on the gag reflex line at the back of the tongue, but a high reading generally means you also have a second colony under the gum. My research shows that specific gum bacteria "Treponema denticola, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythensis, Porphyromonas endodontalis and Eubacterium Species" give off the faeces smell when they are active causing gum disease. This is an extremely predictable gas and probably the most common and offensive smell of halitosis.
Gas 3 - Cabbage With Gasoline
This gas comes from Dimethyl Sulphide, which also comes from the amino acid Methionine. This is the least understood of the bad breath gases. But years of seeing patients and clinically treating bad breath sufferers has proven to me that this gas is an indicator of post nasal drip. My research shows that bacteria accumulate in mucous that collects at the back of the throat can produce this smell. The only way to clear the protein rich biofilm away from the throat area is to include a hypertonic saline spray administered under pressure through the nose so that it can spray to the back of the throat. Sinoclear is such a nasal spray, and is effective when used asa part of the KFORCE PLUS Treatment.
These are usually in very small levels. For example Skatole is due to breakdown of the the amino acid Tryptophan. Cadaverine and Putrescine come from breakdown of the amino acid Lysine. Isovaleric Acid comes from the breakdown of the amino acid Leucine.
You can read some of my research in an article we have had published in the Journal of Applied Microbiology. Burton J, Chilcott C, C. J. Moore, G. Speiser, J. R. Tagg. "A preliminary study of the effect of probiotic Streptococcus salivarius K12 on oral malodour parameters." Journal of Applied Microbiology 2006 pp754-764.