Halitosis can be classified according to its site of generation, and if this is within the oral cavity, then it can be classified as “oral malodor” of microbial origin and accounting for >90% of all halitosis-cases. The “cause” is the presence of VOC-generating microbial biofilms on the mucosa and/or teeth, particularly the dorsum of the tongue, which supports high numbers of microbes as biofilms.
There is general agreement that the degree of bad breath (as reported by trained odour judges) correlates well with objective measurements by analytic instruments. Since all processes in the mouth are continuous, it seems likely that a continuous level of malodour is coupled to a continuous generation rate from the biofilm. This in turn correlates strongly with the quantity (or load) of microbes that can be recovered from the tongue surface. In other words, the amount or thickness (aerial density) of an individual’s biofilm is the most important predictor of bad breath. Oral malodour, tongue biofilm load and ecological composition have been shown to be stable over many months.
The specific theory of oral malodour suggests that specific microbial species are responsible (i.e. aetiological) whilst the non-specific theory suggests that the tongue biofilm “as a whole” is important, without the need for a specific agent (i.e. amount is more important than specific composition). In a diverse biofilm there may be many species that can transform substrates to VSC and many species can “substitute for others” in different cases.
From a modelling perspective, the tongue surface biofilm can be classed as a continuously perfused matrix biofilm system. An in vitro laboratory model using real tongue-derived biofilm as the inoculum may be used to help explain contributing factors that would be occurring in a real mouth, including the application of chemo-preventative treatments. |
