Halitosis: different diagnostic methods for a diverse disease
There are different forms of halitosis – true halitosis (including physiologic or pathological), pseudohalitosis, and halitophobia. Halitosis can be treated only if its etiology can be correctly detected. Appropriate diagnosis can help identify the best treatment options ranging from professional intervention (scaling and root planning) to mechanical and chemical solutions, or their combination (oral hygiene, tongue cleaning, mouth rinsing).
To determine best treatment options, it is important to first identify the presence of an objectively detectable odour and then the source of the halitosis, using detailed examination techniques.
There are several methods available for the objective measurement of halitosis:
With organoleptic methods, halitosis is assessed with the sense of smell and assigned a degree of severity based on odour intensity. The most common classification is between 0 and 5, where 0 denotes undetectable and 5 extreme halitosis .
There are several ways of undertaking this diagnosis, including the "open mouth" method, counting method, "Ha-Ha-Ha" method, glass tube or drinking straw method. The advantage of this approach is that patients receive important information about the evaluation of a human perception threshold for odours. The disadvantage is that the patient often does not trust the "nose" of the examiner. Particularly with pseudohalitosis it is better to choose an instrumental diagnosis.
Instrumental methods are more “scientific” or “impartial” by definition. Gas chromatography is a way of separating and analyzing compounds that can be vaporized. Tonzetich  developed a gas chromatograph that detects a number of volatile sulphides in a patient’s breath, enabling the measurement of hydrogen sulfide, methyl mercaptan, and dimethyl sulfide.
Gas chromatography is relatively complicated and expensive, making this device more appropriate for research than for everyday use.
Smaller devices have therefore been developed to measure volatile sulphur compounds directly in the treatment chair. These include the Halimeter, which basically measures sulphur. The halimeter sucks-in air via a hose and guides it to an electrochemical gas sensor which quickly measures a patient’s concentration of volatile sulphur compounds.
The limitation of this device is that it can't distinguish between the different sulphides, which means it cannot clarify whether the cause is oral or non-oral. In addition, the correlation of the results of the halimeter with those of the organoleptic method is usually poor because halitosis can also be caused by other, sulphur-free compounds, which the halimeter does not measure.
A combination of both the organoleptic and halimeter approach is therefore recommended and can provides important clues to the causes of halitosis.
The BANA test is practical for chair-side usage, and requires only the scraping of the tongue with a cotton swab. The test measures the levels of a specific enzyme produced by halitosis-causing bacteria . By detecting short-chain fatty acids and proteolytic obligate gram-negative anaerobes, it is possible to detect not only halitosis, but also periodontal risk . This approach facilitates planning of treatment and prevention strategies and communication with patients.
Appropriate use of diagnostic tests and clinical examination are crucial to identify the cause of halitosis and recommend the best treatment options. If not properly diagnosed and treated, halitosis has a negative effect on a person's social life. Moreover, halitosis may be a sign of other underlying oral health (or other) conditions.