How academic researchers test for the presence of halitosis.

Before a dental researcher can evaluate the effectiveness of a cure for bad breath they must first have a way to quantify the person's level of malodor, both initially and after the cure they are studying has been administered. Some of the different methods researchers use to measure bad breath are discussed below.


Organoleptic testing for bad breath.
Judging a person's breath by way of organoleptic testing simply means that the researcher performing the breath evaluation has used their sense of smell (their nose) as the means for making a determination. Historically this method of breath testing has been a frequent choice among dental researchers. Noses are readily available, inexpensive to obtain and operate, and to their credit, noses can detect up to 10,000 different smells.

One of the problems associated with using organoleptic testing is that this technique is not totally objective. Another is that factors other than just breath odors can and do influence organoleptic evaluations. As examples, research has shown that factors such as hunger, menstrual cycle, head position, and the degree of attentiveness and expectation can each influence a judge's interpretation of what they smell. Additionally, consumption or use of coffee, tea, juice, tobacco products and scented cosmetics by subjects prior to their evaluation can influence the testing.

As for quantifying the organoleptic measurement itself, what exactly does constitute a weak, strong, or average level of bad breath? Will each judge participating in the research be able to make equivalent comparisons? Complicating things even more, as we all know, when we are repeatedly exposed to a bad odor our sense of smell acclimates to the odor and therefore loses much of its sensitivity. Breath malodor that seems exceedingly objectionable at the beginning of testing may seem quite less so as the evaluation continues.


Evaluating bad breath with gas chromatography.
A number of scientific fields utilize gas chromatographs to identify compounds found in the samples they are studying. Likewise, gas chromatographs have been employed by dentists conducting halitosis studies and have provided a means by which a researcher can definitively quantify the precise levels of various compounds present in someone's breath. It is considered to be the "gold standard" for measuring breath malodor.

While gas chromatography is probably the best way to test for the compounds associated with bad breath, it has not been widely utilized in research studies for several reasons. Gas chromatographs are relatively expensive and require personnel with special training to operate them. The equipment is not portable and a significant amount of time is needed to make each breath measurement.


Using Halimeters to quantify halitosis (see our shop to get one!)
A specialized type of sulfide monitor (termed a Halimeter) has been developed and it provides a means by which a tester can quantify certain aspects of a person's breath. These machines, first introduced in 1991, measure levels of sulfide gases. Some sulfides, such as hydrogen sulfide and methyl mercaptan (collectively referred to in dental literature as volatile sulfur compounds or "VSC's"), are known to be causative agents of bad breath. A Halimeter's reading showing a high level of sulfides in a person's breath suggests that a corresponding high level of VSC's are present, although the apparatus does not test for individual types of VSC's specifically.

Since a Halimeter tests for a fewer number of compounds (sulfides only) than gas chromatographs, and in fact test for no individual compounds at all but instead just sulfides as a class, Halimeters provide for a less definitive evaluation of a person's breath malodor than gas chromatographs. Additionally, compounds such as ethanol (alcohol) and essential oils (both of which are frequently found in mouthwashes) interfere with a Halimeter's ability to make a measurement. The advantages of using a Halimeter for a study rather than a gas chromatograph are that a Halimeter requires no special training to use, is portable, breath measurements can be made quickly and the apparatus itself is comparatively inexpensive.


The BANA test.
Some of the bacteria that cause periodontal disease (gum disease) produce waste products that are quite odiferous and as a result contribute to a person's breath problems. The presence of some of these types of bacteria can be tested for by way of performing a BANA test.

The bacteria in question have the characteristic of being able to produce an enzyme that degrades the compound benzoyl-D, L-arginine-naphthylamide (abbreviated BANA). When a sample of a patient's saliva that contains these bacteria is placed in with the BANA testing compound they cause it to break down, thus creating a color change in the testing medium.


Utilizing chemiluminescence to detect bad breath.
One of the more recently developed methods of testing for the presence of compounds associated with bad breath relies on the principle of chemiluminescence. This type of testing was first introduced in 1999. When a sample containing sulfur compounds (such as VSC's, the types of compounds which cause bad breath) is mixed in with the test's mercury compound, the resulting reaction causes fluorescence. The strength of chemiluminescence methodology is that it can provide better selectivity and sensitivity when measuring low levels of sulfur compounds, as compared to testing with a Halimeter.