Bad breath

Did You Know?

• Bad breath is viewed as a social taboo and those affected may be stigmatized.
• It is believed to become more common as people age.

Causes

In about 90% of genuine halitosis cases, the odor originates within the mouth, termed intra-oral halitosis. The most common cause is a biofilm on the back of the tongue or other oral surfaces due to poor hygiene, which breaks down proteins into amino acids and then into foul-smelling gases, including volatile sulfur compounds. Other oral contributors, in descending order of prevalence, include inter-dental and sub-gingival niches, faulty dental work, food-impaction areas, abscesses, and unclean dentures. Viral infections such as herpes simplex and HPV can also play a role. Breath odor intensity can vary during the day, influenced by foods like garlic, onions, meat, fish, and cheese, as well as smoking and alcohol consumption. It is typically worse upon waking due to reduced oxygen and inactivity overnight. Bad breath may be transient, resolving with eating, drinking, or oral hygiene, or persistent, affecting about 25% of the population to some degree.

Diagnosis

Five examination methods are used to diagnose halitosis: self-assessment, others' assessment, organoleptic examination, chemical and enzymatic tests, and halitometry. Chemical and enzymatic tests detect bacterial species, their metabolic products, or enzymes, while halitometers quantify gases but do not directly detect halitosis. Examinations by the human nose—self-assessment, feedback from others, or organoleptic examination by an examiner—directly target the odor, but organoleptic examination alone is insufficient when the individual has no complaint. Diagnosis and tracking of halitosis primarily depend on self-assessment and feedback from others, which motivate individuals to seek treatment. Smelling one's own breath is often difficult due to acclimatization, and self-evaluation is complicated by preconceived notions. A bad taste (metallic, sour, fecal) is considered a poor indicator. Patients often ask a close friend for an opinion. A common home test—licking the wrist and smelling the dried saliva—tends to overestimate halitosis and should be avoided; a better method is scraping the back of the tongue with a plastic spoon and smelling the residue. Home chemical tests for polyamines and sulfur compounds exist, but few studies confirm their accuracy. Because breath odor changes throughout the day, multiple testing sessions may be needed.

Management

Approaches to improve bad breath include physical or chemical means to reduce oral bacteria, masking products, or chemicals that alter odor molecules. Interventions such as toothpastes, mouthwashes, lasers, tongue scraping, and mouth rinses have been tried, but there is no strong evidence indicating which are most effective. Tobacco users are advised to stop. Brushing teeth may help, and tongue cleaning shows tentative benefit, though evidence is insufficient for firm conclusions. Flossing may also be useful. Mouthwashes often contain antibacterial agents like cetylpyridinium chloride, chlorhexidine, zinc compounds, hydrogen peroxide, chlorine dioxide, amine fluorides, stannous fluoride, hinokitiol, and essential oils; cetylpyridinium chloride and chlorhexidine can temporarily stain teeth. If gum disease or cavities are present, treatment is recommended. For causes outside the mouth, addressing the underlying condition may improve breath. Counseling can benefit those who falsely believe they have bad breath.

History, society and culture

The earliest known mention of bad breath is from ancient Egypt, where toothpaste recipes predate the Pyramids. Hippocratic medicine recommended a mouthwash of red wine and spices, though alcohol-containing mouthwashes are now thought to worsen breath by drying the mouth. The Hippocratic Corpus also includes a marble-powder recipe for women with bad breath. A Greek-language Roman joke collection includes jokes on the topic. Ancient Chinese emperors required visitors to chew clove before an audience. The Talmud considers bad breath a disability that could justify breaking a marriage license. Early Islamic theology promoted cleaning teeth and tongue with a siwak (miswak) from the Salvadora persica tree. During the Renaissance, Laurent Joubert, a French royal doctor, attributed bad breath to dangerous miasma affecting the lungs and heart. A 1919 health book offers a post-meal mixture of chloride of soda, liquor of potassa, phosphate of soda, and water.