Cleared the field by misunderstanding very frequently report that ’s halitosis in the presence of general diseases, we can concentrate on the most common cause that resides in oral pathological conditions in which the halitosis can be reduced, as we have said, in about 90% of cases.  When in the oral cavity there are very extensive cariose lesions (tooth decay), periodontal problems and in any case a failure to monitor oral hygiene, significantly increases the amount of bacteria that have gram-anaerobic metabolism voluntary or forced.
These bacteria cause the putrefaction of organic substances contained in saliva protein, residues in food and blood in mouth in the case of gingivitis and periodontitis. As a result of their action in this way are called composite volatile sulfur compounds including hydrogen sulphide, the Methyl mercaptan, amino compounds such as putrescine and cadaverine.