Bias

This finding is also confirmed by epidemiological studies performed on large population samples. Self-perception questionnaires and subsequent breath tests (by means of devices which measure levels of VSCs and organoleptic tests on exhaled air by odour “judges”) completed by thousands of people have demonstrated that there is no statistically-relevant association between the self-perception of halitosis and genuine cases of bad breath.

If fact, many people complain of halitosis without actually suffering from it. On the other hand, individuals with genuine halitosis are often completely unaware of their condition due to olfactory fatigue (getting used to one’s own odour). Contrary to what most of us believe, it is becoming increasingly clear that the self-perception of halitosis is a method that is highly susceptible to bias.

This is why self-perception should not be used as method for diagnosing halitosis, either by patients themselves (to avoid arriving at mistaken conclusions about their own breath) or by healthcare professionals (when designing treatment plans). In addition to this method’s low reliability, there are various psychological and psychiatric conditions that can influence a person’s self-perception and/or even how they believe others perceive their breath (neuropsychological halitosis).