What to do about halitosis

A degree of halitosis (oral malodour or foetor oris) is common in healthy people, particularly after sleep. It seems to originate from the mouth, resulting from the metabolic activity of bacteria present in oral plaque. Halitosis at other times is a distressing complaint from which few people probably escape completely and which is still incompletely understood. The true prevalence is not known, but one recent study suggested that nearly half of a group of young women (dental hygienists) believed that they sometimes had halitosis.1

Halitosis generally has as its basis bacterial putrefaction of food debris, cells, saliva, and blood.2 In particular, proteolysis of proteins to peptides, amino acids, and thence substrates with free thiol groups, such as cysteine and reduced glutathione, gives rise to volatile fluids and sulphides.3 Acetone, acetaldehyde, ethanol, propanol, and diacyl are also important causes of halitosis but, perhaps surprisingly, amines, indole, and skatole do not seem to be aetiologically important.4

People who refrain from cleaning their mouth soon develop halitosis,5 but any form of oral sepsis can produce appreciable malodour, the most common condition being inflammatory, plaque related gingival disease (gingivitis) or periodontal disease (periodontitis). The amounts of volatile sulphur compounds and the ratio of methylmercaptan to hydrogen sulphide are higher in the mouth air from patients with periodontal disease than in that from people with healthy mouths.^6,7 The source of these compounds seems to be the gingival crevice, periodontal pockets, and the tongue coating.^6,7 Sulphides identified from gingival crevicular sites include hydrogen sulphide, methylmercaptan, dimethyl sulphide, and dimethyl disulphide.8 Concentrations of these sulphides in mouth air seem to be particularly associated with oral spirochaetes and motile rods.9 Other oral sources of infection can cause malodour, as can sinusitis, foreign bodies in the nose, and respiratory infections.

Many foods and drinks can cause transient malodour, especially garlic, onions, and curries. Smoking and drugs, including occasionally alcohol, isosorbide dinitrate, and disulfiram, may also be implicated. Rare causes include diabetic ketoacidosis and severe renal or hepatic dysfunction. A recent possible link has been suggested between Helicobacter pylori and halitosis,10 but this is unsubstantiated. Halitosis may also be imaginary (delusional halitosis)11 or a hallucinatory feature in schizophrenia or temporal lobe epilepsy.

The management of halitosis requires establishing the presence of true halitosis and assessing its severity. People are usually good judges of the degree of malodour but, as measurement of sulphide concentrations in mouth air is reproducible and sensitive and relates well to assessments of malodour assessment by observers,^12,13 measurement with a portable sulphide monitor provides an objective assessment. Gas chromatography may provide a more accurate assessment of the wider range of compounds responsible for malodour and has been adapted for use with small samples of mouth air.4 The history and examination should be directed towards eliminating any dietary and systemic causes. A full assessment of oral and dental health is always indicated, and, although a dental practitioner is the best trained for this, a periodontologist has special skill in disorders affecting the gingiva and periodontium.

The most reliable management is to reduce the oral flora, particularly anaerobes; this is best achieved by improving oral hygiene by brushing the teeth, cleaning between the teeth, and other means. A simple, inexpensive, and effective treatment is to use a mouth rinse of 0.2% aqueous chlorhexidine gluconate, which is remarkably active against a range of organisms in dental plaque and can also reduce halitosis whether judged subjectively or by decreases in volatile sulphides in the mouth air.13 Hydrogen peroxide mouthwashes reduce concentrations of salivary thiols and may be useful in the management of acute necrotising (ulcerative) gingivitis, but they are not indicated in most other oral infections. Antimicrobial treatment is rarely needed except in severe or recalcitrant cases, though it can be useful to reduce postoperative halitosis.14

Various other products designed to reduce halitosis are under development. For example, cetylpyridinium chloride and a two phase oil-water mouthwash containing olive and other essential oils15 seem to reduce volatile sulphur compounds in the breath.^15,16 A range of mouth fresheners is also available. Currently, however, the cheapest and most effective management for most cases of halitosis is simple, regular oral cleaning with a toothbrush and dental floss.