The vast majority of oral malodor originates with the anaerobic bacterial degradation of sulfur containing amino acids within the oral cavity, resulting in the emission of hydrogen sulfide (H2S), methyl mercaptan (CH3SH), and dimethyl sulfide (CH3SCH3), collectively referred to as volatile sulfur compounds (VSC).
The Halimeter® responds to all three volatile sulfur compounds, and gives a reading of total VSC’s.
To be rigorous, the Halimeter does not respond equally to all three compounds, nor are all three compounds present in the same proportion in all patients—or even in the same patient—at all times. The relative amounts of these compounds are affected by diet, and the extent of anaerobic bacterial growth.
Elucidating the precise breakdown of the three compounds in an oral malodor sample requires a gas chromatograph, an instrument clearly beyond the scope of the typical dental office, and rare enough even in academic dental research settings. Fortunately, the additive reading provided by the Halimeter correlates extremely well with organoleptic panels of trained human olfactory evaluators, and compares admirably with chromatographic testing.
The Halimeter reads out in parts-per-billion (ppb) of volatile sulfur compounds.
As was emphasized in the Knowledge Base article “The importance of proper breath sampling technique–with recommendations”, numerical readings can be greatly affected by variations in breath sampling technique. Please note that the interpretations discussed below are based on following the sampling technique described in that article.
Many practitioners have developed their own sampling techniques, some of which do not incubate the sample for as long as we recommend, and some of which might be more prone to dilution from the ambient air.
The question arises: Are these sampling techniques “wrong”?
They are only wrong if one wishes to produce VSC readings conforming to the interpretations discussed below. However, if alternative sampling techniques are practiced with consistency, good results can be obtained, and will conform in a RELATIVE sense with our numerical scale. It is noted that alternative sampling techniques will usually produce lower readings
- Normal readings, for subjects with no oral malodor, are generally in the range of 80-140 parts per billion (ppb). Readings lower than this range are still indicative of no oral malodor, and are otherwise clinically inconsequential.
- At levels of 200-300 ppb, oral malodor is noticeable by an observer standing close to the patient.
- At 350-400 ppb, the odor is noticeable by an observer standing several feet away from the patient.
- At 500-700 ppb the odor is more noticeable not because it is “stronger,” but because it is more foul.
- At over 1000 ppb, the odor will linger for several minutes after the patient leaves the room. In many of these cases, odor will continue to emanate from the tongue during the entire sampling process, and the Halimeter reading will keep climbing, and may not truly peak, as the sample pump seems to draw more VSC’s off the tongue surface. Removal of the tongue coating should eliminate this phenomenon.
High readings can also be produced by interfering compounds, such as flavoring agents in mouthrinses, mints, and herbal teas. The Halimeter is reading in the parts-per-billion range, and some of these flavoring agents can be present at oral concentrations several orders of magnitude higher. This is one reason why we recommend that the patient should refrain from food, smoking, drinking (water is allowed), and oral hygiene for 3-4 hours before the testing.
If you wish to investigate the therapeutic effect of a rinse, or a procedure that may introduce a flavoring agent into the mouth, make sure that the patient rinses thoroughly with plain water, and allow sufficient time for the aromatic sensation to dissipate, before taking a Halimeter reading.
As with all biological parameters, Halimeter readings should be used not so much as absolute standards, but as relative indicators of a condition. That is, a normal blood pressure reading is said to be 120/80. While 180/110 would be an indication that the patient should seek further medical attention, a reading of 130/82 would not. Similarly, normal blood glucose level is said to be 100 mg/dl, but is better defined as a range of 70-115 mg/dl.
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