Approach

The diagnostic approach to halitosis is largely based on medical history, clinical examination, and patient history. This is supported by the fact that 85% to 90% of cases of persistent halitosis are due to oral causes.[1][2][3][9] These include, although rarely, malignancy of the mouth. Respiratory, gastrointestinal (GI), and metabolic diseases account for the remaining 10% to 15% of patients.[2][3][9][10][11][15][16] GI disorders in particular have been traditionally considered a common cause of halitosis, especially by clinicians. However, current evidence suggests that this association is extremely rare, and it is important to highlight here that more common causes should be addressed first when a patient with halitosis is approached. Malignancy of the upper respiratory and GI tracts can cause halitosis, although this is a rare occurrence. Halitosis due to malignancy comes from superficial necrosis, ulceration, and secondary infection. This characterises advanced cancer, and there are usually further associated signs and symptoms. These include visual and endoscopic evidence of an ulcerated mass, head and neck lymphadenopathy, dysphagia and odynophagia, trismus, and ankyloglossia. Cough, chest pain, and haemoptysis are typical for malignancy of the respiratory tract.

History

First, it is important to understand whether a given complaint of halitosis is justified, because most people are poor judges of their own breath odour. As a consequence, they may have an unjustified fear that they have bad breath or, conversely, they may be unaware of their bad breath (known as 'bad breath paradox').[1][19]

In general, the following symptoms can be warning signs of pseudo-halitosis:[20]

  • Obsessive behaviour

  • Depression

  • Phobic anxiety

  • Paranoid ideation

  • Reduced social interactions

  • Wrong interpretation of other's actions (e.g., opening windows, covering noses) as indications that the patient's breath is offensive.

Another important aspect of history collection is to ask whether other people close to the patient (e.g., partner, friends, relatives) can perceive the reported bad breath.

If breath malodour is not identified during the initial examination, assessment for halitosis should be repeated on 2 or 3 different days. If it is still not present, pseudo-halitosis should be considered. This is a diagnosis that can be supported by questionnaires validated to survey the causes of halitosis and psychosomatic tendencies.[2] However, history collection is usually not sufficient to categorise a patient under the label of pseudo-halitosis. Pseudo-halitosis is a diagnosis of exclusion and therefore it requires the presence of pathological halitosis to be ruled out.

Enquiring about the patient's diet will help to identify blood-borne halitosis related to odorous foodstuffs.

Risk/predisposing factors (local)

There are numerous local factors that can increase the accumulation of bacteria on oral and nasopharyngeal surfaces. Treatment of these factors usually leads to resolution of associated bacterial accumulation and, hence, of halitosis. They include:

  • Oral disease (food impaction, acute necrotising ulcerative gingivitis, acute gingivitis, adult and aggressive periodontitis, pericoronitis, dry socket, xerostomia, oral ulceration, and oral malignancy)

  • Nasopharyngeal disease (foreign body, sinusitis, tonsillitis, tonsilloliths, cleft palate, and nasopharyngeal malignancy).

Because some features of oral and nasopharyngeal disease can be hard to detect at visual inspection in primary care (using gloves and gauze only), referral to a consultant (dentist, maxillofacial, and/or ENT surgeon) may be necessary to carefully evaluate the patient's status with appropriate diagnostic tools.

Subjective clinical examination

Clinical assessment of oral malodour is important and should be performed by 2 different examiners. The assessment is usually based on the clinician sniffing the air exhaled from the mouth and nose, and subjectively assessing the presence or absence of malodour.[1][2][3] Assessing air from both the nose and the mouth is important, as malodour detectable from the nose alone (asking the patient to breathe while the mouth is closed) is likely to be arising from the nose or sinuses.[3][19]

It is advisable that the patient abstains from eating garlic, onion, and spicy food for 48 hours before the assessment.

Both the patient and the clinician should refrain from drinking coffee, tea, or juice, as well as from smoking and using scented cosmetics, before the assessment.[2]

There is usually no clinical indication for an assessment of the quality of the odour (the hedonic method has been used and it relies upon trained clinical judges and is more relevant to translational research).[21]

A series of organoleptic tests that can be performed during clinical examination have been suggested.[22] These include:

  • Sniffing test: the clinician sniffs the exhaled air from 10 cm distance after the patient's mouth has been closed for 2 minutes.

  • Count-to-twenty test: the clinician sniffs the exhaled air from 10 cm distance while the patient counts up to twenty.

  • Wrist-lick test: the patient is asked to lick his/her wrist, whereupon the clinician sniffs the wrist from 5 cm distance.

  • Spoon test: a plastic spoon is used to gently scratch the lingual dorsum to collect epithelial cells and microbial film. The clinician sniffs the spoon from 5 cm distance.

  • Flossing test: the patient is asked to floss his molar teeth, and the clinician sniffs the floss from 3 to 5 cm distance.

Objective clinical examination

More objective measurements of halitosis are available but they are not used in routine clinical practice, as they are expensive and time consuming.[1][2][3]

  • Portable sulfide monitors can measure total volatile sulfur compounds (VSCs), but not the other volatile agents that can cause oral malodour.

  • An optical bio-sniffer for the detection of methyl mercaptan has been suggested to be of potential application, but it remains unclear if this has any clinical value.[23]

  • Gas chromatography is considered the diagnostic standard for measuring oral malodour because it is specific for different VSCs. It is cumbersome, however, needs adequate training, and is mainly used in the research setting. Selected ion flow tube mass spectroscopy has been shown to be a means of estimating VSCs and non-sulfides in breath, but this is not considered to be clinically practical.[24]

Identifying halitosis bacteria

Bacteria likely to give rise to oral malodour can be detected via several different techniques. However, these are of little application to the present care of patients with oral malodour.[25][26]

The techniques include:

  • Detection of trypsin-like activities of bacteria, the benzol-arginine-naphthylamide (BANA) test

  • Dark-field microscopy

  • Real-time quantitative polymerase chain reaction.

Risk/predisposing factors (systemic)

A spectrum of systemic disorders may rarely give rise to halitosis, but as a symptom halitosis is unlikely to be of notable diagnostic importance, and indeed, is of minor consideration in patient care.[2][3][15][16] These disorders include:

Upper GI tract

  • Oesophageal diverticulum

  • GORD

  • Malignancy.

Respiratory system

  • Infections

  • Bronchiectasis

  • Lung abscess

  • Malignancy.

Hepatic disease

  • Hepatic failure (fetor hepaticus).

Renal disease

  • Renal failure (end-stage renal failure).

Endocrine disease or hormonal changes

  • Diabetic ketoacidosis

  • Menstruation (menstrual breath).

Metabolic disease

  • Trimethylaminuria

  • Hypermethioninaemia.

These disorders can be suspected in the absence of identifiable local causes of halitosis and when further systemic symptoms/signs are present (e.g., halitosis due to oropharyngeal or laryngeal malignancy can be associated with endoscopic evidence of an ulcerated mass, head and neck lymphadenopathy, dysphagia and odynophagia; cough, chest pain, and haemoptysis are typical for malignancy of the respiratory tract).

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