has suggested that self-evaluation of halitosis is not easy because of preconceived notions of how bad we think it should be. some people assume that they have bad breath because of bad taste (metallic, sour, fecal, etc.), however bad taste is considered a poor indicator. patients often self-diagnose by asking a close friend. one popular home method to determine the presence of bad breath is to lick the back of the wrist, let the saliva dry for a minute or two, and smell the result. this test results in overestimation, as concluded from research, and should be avoided. a better way would be to lightly scrape the posterior back of the tongue with a plastic disposable spoon and to smell the drying residue. home tests that use a chemical reaction to test for the presence of polyamines and sulfur compounds on tongue swabs are now available, but there are few studies showing how well they actually detect the odour. furthermore, since breath odour changes in intensity throughout the day depending on many factors, multiple testing sessions may be necessary. testing if bad breath is persistent, and all other medical and dental factors have been ruled out, specialized testing and treatment is required. hundreds of dental offices and commercial breath clinics now claim to diagnose and treat bad breath. they often use some of several laboratory methods for diagnosis of bad breath: halimeter: a portable sulfide monitor used to test for levels of sulfur emissions (to be specific, hydrogen sulfide) in the mouth air. when used properly, this device can be very effective at determining levels of certain vsc-producing bacteria. however, it has drawbacks in clinical applications. for example, other common sulfides (such as mercaptan) are not recorded as easily and can be misrepresented in test results. certain foods such as garlic and onions produce sulfur in the breath for as long as 48 hours and can result in false readings. the halimeter is also very sensitive to alcohol, so one should avoid drinking alcohol or using alcohol-containing mouthwashes for at least 12 hours prior to being tested. this analog machine loses sensitivity over time and requires periodic recalibration to remain accurate. gas chromatography: portable machines are being studied. this technology is designed to digitally measure molecular levels of major vscs in a sample of mouth air (such as hydrogen sulfide, methyl mercaptan, and dimethyl sulfide). it is accurate in measuring the sulfur components of the breath and produces visual results in graph form via computer interface. bana test: this test is directed to find the salivary levels of an enzyme indicating the presence of certain halitosis-related bacteria. β-galactosidase test: salivary levels of this enzyme were found to be correlated with oral malodour. although such instrumentation and examinations are widely used in breath clinics, the most important measurement of bad breath (the gold standard) is the actual sniffing and scoring of the level and type of the odour carried out by trained experts ("organoleptic measurements"). the level of odour is usually assessed on a six-point intensity scale. classification two main classification schemes exist for bad breath, although neither are universally accepted. the miyazaki et al. classification was originally described in 1999 in a japanese scientific publication, and has since been adapted to reflect north american society, especially with regards halitophobia. the classification assumes three primary divisions of the halitosis symptom, namely genuine halitosis, pseudohalitosis and halitophobia. this classification has been suggested to be most widely used, but it has been criticized because it is overly simplistic and is largely of use only to dentists rather than other specialties. genuine halitosis a. physiologic halitosis b. pathologic halitosis (i) oral (ii) extra-oral pseudohalitosis halitophobia the tangerman and winkel classification was suggested in europe in 2002. this classification focuses only on those cases where there is genuine halitosis, and has therefore been criticized for being less clinically useful for dentistry when compared to the miyazaki et al. classification. intra-oral halitosis extra-oral halitosis a. blood borne halitosis (i) systemic diseases (ii) metabolic diseases (iii) food (iv) medication b. non-blood borne halitosis (i) upper respiratory tract (ii) lower respiratory tract the same authors also suggested that halitosis can be divided according to the character of the odour into 3 groups: "sulfurous or fecal" caused by volatile sulfur compounds (vsc), most notably methyl mercaptan, hydrogen sulfide and dimethyl sulfide. "fruity" caused by acetone, present in diabetes. "urine-like or ammoniacal" caused by ammonia, dimethyl amine and trimethylamine (tma), present in trimethylaminuria and uremia. based on the strengths and weaknesses of previous attempts at classification, a cause based classification has been proposed: type 0 (physiologic) type 1 (oral) type 2 (airway) type 3 (gastroesophageal) type 4 (blood-borne) type 5 (subjective) any halitosis symptom is potentially the sum of these types in any combination, superimposed on the physiologic odour present in all healthy individuals. management approaches to improve bad breath may include physical or chemical means to decrease bacteria in the mouth, products to mask the smell, or chemicals to alter the odour creating molecules. many different interventions have been suggested and trialed such as toothpastes, mouthwashes, lasers, tongue scraping, and mouth rinses. there is no strong evidence to indicate which interventions work and which are more effective. it is recommended that in those who use tobacco products stop. evidence does not support the benefit of dietary changes or chewing gum. mechanical measures brushing the teeth may help. while there is evidence of tentative benefit from tongue cleaning it is insufficient to draw clear conclusions. a 2006 cochrane review found tentative evidence that it might decrease levels of odour molecules. flossing may be useful. mouthwashes a 2008 systematic review found that antibacterial mouthrinses may help. mouthwashes often contain antibacterial agents including cetylpyridinium chloride, chlorhexidine, zinc gluconate, zinc chloride, zinc lactate, hydrogen peroxide, chlorine dioxide, amine fluorides, stannous fluoride, hinokitiol, and essential oils. listerine is one of the well-known mouthwash products composed of different essential oils. other formulations containing herbal products and probiotics have also been proposed. cetylpyridinium chloride and chlorhexidine can temporarily stain teeth. underlying disease if gum disease and cavities are present, it is recommended that these be treated. if diseases outside of the mouth are believed to be contributing to the problem, treatment may result in improvements. counselling may be useful in those who falsely believe that they have bad breath. epidemiology it is difficult for researchers to make estimates of the prevalence of halitosis in the general population for several reasons. firstly, halitosis is subject to societal taboo and stigma, which may impact individual's willingness to take part in such studies or to report accurately their experience of the condition. secondly, there is no universal agreement about what diagnostic criteria and what detection methods should be used to define which individuals have halitosis and which do not. some studies rely on self reported estimation of halitosis, and there is contention as to whether this is a reliable predictor of actual halitosis or not. in reflection of these problems, reported epidemiological data are widely variable. history, society and culture the earliest known mention of bad breath occurs in ancient egypt, where detailed recipes for toothpaste are made before the pyramids are built. the 1550 bc ebers papyrus describes tablets to cure bad breath based on incense, cinnamon, myrrh and honey. hippocratic medicine advocated a mouthwash of red wine and spices to cure bad breath. alcohol-containing mouthwashes are now thought to exacerbate bad breath as they dry the mouth, leading to increased microbial growth. the hippocratic corpus also describes a recipe based on marble powder for females with bad breath. the ancient roman physician pliny wrote about methods to sweeten the breath. ancient chinese emperors required visitors to chew clove before an audience. the talmud describes bad breath as a disability, which could be grounds for legal breaking of a marriage license. early islamic theology stressed that the teeth and tongue should be cleaned with a siwak, a stick from the plant salvadora persica tree. this traditional chewing stick is also called a miswak, especially used in saudi arabia, an essentially is like a natural toothbrush made from twigs. during the renaissance era, laurent joubert, doctor to king henry iii of france states bad breath is "caused by dangerous miasma that falls into the lungs and through the heart, causing severe damages". in b. g. jefferis and j. l. nichols' "searchlights on health" (1919), the following recipe is offered: " teaspoonful of the following mixture after each meal: one ounce chloride of soda, one ounce liquor of potassa, one and one-half ounces phosphate of soda, and three ounces of water." in the present day, bad breath is one of the biggest social taboos. the general population places great importance on the avoidance of bad breath, illustrated by the annual $1 billion that consumers in the united states spend on deodorant-type mouth (oral) rinses, mints, and related over-the-counter products. many of these practices are merely short term attempts at masking the odour. some authors have suggested that there is an evolutionary basis to concern over bad breath. an instinctive aversion to unpleasant odours may function to detect spoiled food sources and other potentially invective or harmful substances. body odours in general are thought to play an important role in mate selection in humans, and unpleasant odour may signal disease, and hence a potentially unwise choice of mate. although reports of bad breath are found in the earliest medical writings known, the social stigma has likely changed over time, possibly partly due to sociocultural factors involving advertising pressures. as a result, the negative psychosocial aspects of halitosis may have worsened, and psychiatric conditions such as halitophobia are probably more common than historically. there have been rare reports of people committing suicide because of halitosis, whether there is genuine halitosis or not. etymology the word halitosis is derived from the latin word halitus, meaning 'breath', and the greek suffix -osis meaning 'diseased' or 'a condition of'. with modern consumerism, there has been a complex interplay of advertising pressures and the existing evolutionary aversion to malodour. contrary to the popular belief that listerine coined the term halitosis, its origins date to before the product's existence, being coined by physician joseph william howe in his 1874 book the breath, and the diseases which give it a fetid odor, although it only became commonly used in the 1920s when a marketing campaign promoted listerine as a solution for "chronic halitosis". the company was the first to manufacture mouth washes in the united states. according to freakonomics: listerine "...was invented in the nineteenth century as powerful surgical antiseptic. it was later sold, in distilled form, as both a floor cleaner and a cure for gonorrhea. but it wasn't a runaway success until the 1920s, when it was pitched as a solution for "chronic halitosis"— a then obscure medical term for bad breath. listerine's new ads featured forlorn young women and men, eager for marriage but turned off by their mate's rotten breath. "can i be happy with him in spite of that?" one maiden asked herself. until that time, bad breath was not conventionally considered such a catastrophe, but listerine changed that. as the advertising scholar james b. twitchell writes, "listerine did not make mouthwash as much as it made halitosis." in just seven years, the company's revenues rose from $115,000 to more than $8 million." alternative medicine according to traditional ayurvedic medicine, chewing areca nut and betel leaf is a remedy for bad breath. in south asia, it was a custom to chew areca or betel nut and betel leaf among lovers because of the breath-freshening and stimulant drug properties of the mixture. both the nut and the leaf are mild stimulants and can be addictive with repeated use. the betel nut will also cause dental decay and red or black staining of teeth when chewed. both areca nut and betel leaf chewing, however, can cause premalignant lesions such as leukoplakia and submucous fibrosis, and are recognized risk factors for oral and oropharyngeal squamous cell carcinoma (oral cancer). practitioners and purveyors of alternative medicine sell a vast range of products that claim to be beneficial in treating halitosis, including dietary supplements, vitamins, and oral probiotics. halitosis is often claimed to be a symptom of "candida hypersensitivity syndrome" or related diseases, and is claimed