17/09/2026
Halitosis can arise from five clinical types and three main sources. In this lecture, I summarize the main examination methods used to distinguish oral and non-oral halitosis, with particular emphasis on the cysteine challenge test.
The cysteine challenge test, first introduced by Kleinberg in 2002, uses cysteine to stimulate maximum oral malodor production. The test can help identify an individual's tendency to develop oral halitosis, even when halitosis is not measurable at the exact moment of examination.
After the patient's baseline oral H₂S level is measured, a rinse is used to stimulate production. The maximum post-cysteine level is then compared with the baseline level. A maximum-to-baseline ratio exceeding 12 is interpreted in favor of oral halitosis.
📄 Test – Diagnostic Protocol:
https://www.drmurataydin.com/cysteine-challenge-diagnostic.pdf
Some patients may have no measurable halitosis during a particular examination, even though they have a tendency to produce oral malodor. The cysteine challenge test may help reveal these cases.
🎥 Hidden Halitosis Case 1:
https://youtu.be/JSZSWy_jKMk
🎥 Hidden Halitosis Case 2:
https://youtu.be/XTNG31nasS4
Limitations of current halitosis examination methods
Self-assessment and assessment by others may lead patients to seek medical care because they believe they have halitosis or they have recovered.
Chemical and enzymatic tests, including β-galactosidase, ninhydrin and , can provide information about bacteria and their metabolic products, but they do not directly measure halitosis.
Similarly, measures specific gases rather than .
The examination is widely accepted in the halitosis literature, but it has important methodological limitations, including subjective perception, nonlinear odor perception, lack of standardization, infection concerns, irreproducibility and difficulties in training and calibration.
📄 Organoleptic Examination Review:
https://www.drmurataydin.com/organoleptic-examination.pdf
