Background

The cysteine challenge test is often used to check the H2S production capacity of the mouth. Patients with oral halitosis group (n=305) or non-oral halitosis group (n=191) and healthy individuals (control group, n=102) were compared with each other to identify any possible relationship between initial and cysteine-induced oral H2S concentrations.

Subjects and Method

Medical records of 598 participants were reviewed retrospectively. Oral H2S concentrations before (pre-CR) and after cysteine rinse (post-CR) with 5 ml of 20 mmol L-cysteine solution for 30 seconds were compared.

Results

Pre-CR H2S concentrations were >0.8ppm in 75.1% of oral group patients but less than <0.8 ppm in 87.3% of non-oral group and 86.9% of controls. After cysteine rinse, oral H2S concentrations exceeded 12 ppm in 72% of oral halitosis patients but were lower in 88% of non-oral group and 99% of controls. While post-CR/pre-CR ratio was >12 in 74.5% of oral group, it was <12 in 81.7% of non-oral group and 83.4% of controls.

Conclusion

Cysteine challenge test can be used as a diagnostic tool to identify an individual's tendency to produce oral malodor, not only to quantify momentary halitosis level.