Reproducibility and sensitivity of oral malodor measurements with a portable sulphide monitor.

Forty-one subjects with bad breath were assessed for oral malodor and periodontal status on three occasions, at intervals of approximately one week. Oral malodor was assessed by measurement of peak and steady-state volatile sulphide levels with a portable sulphide monitor and by organoleptic measurement of whole-mouth, tongue dorsum, and interproximal dental odors by two independent judges. Reproducibility of measurements, assessed by paired t tests and Kappa testing, demonstrated no significant differences between any of the test results from the first and second appointments. Steady-state sulphide levels were the most reproducible of all tests. The ability of the tests to detect an expected reduction of malodor following a 0.2% chlorhexidine mouthrinse regimen was investigated by comparison of test values between the second and third appointments. Following the mouthrinsing treatment, 43% reductions of peak, 47% reductions of steady-state volatile sulphide levels, and 15-58% reductions in all other measurement categories were observed. The majority of the participants (22/41) had no pockets greater than 5 mm and exhibited both moderate gingival inflammation (Mean Gingival Index = 1.17) and moderate plaque accumulation (Mean Plaque Index = 1.84). Plaque Index and presence of pockets greater than 7 mm were weakly related to sulphide measurements. Whereas assessment of steady-state sulphide levels by the sulphide monitor does not constitute a direct measure of oral malodor, its relation to organoleptic measurement, superior reproducibility, objectivity, and sensitivity support the use of the sulphide monitor in clinical studies.