Development of a Simple New Method to Detect Oral Malodor Using a Hydrogen Sulfide Detector Tube

Many patients visit dental clinics complaining of oral malodor. However, there is no simple, inexpensive tool for assessing oral malodor. Therefore, this study developed a simple method using a detector tube.

A detector tube was created to detect hydrogen sulfide based on the color change of an indicator (GASTEC, Kanagawa, Japan). We confirmed the ability to detect hydrogen sulfide concentrations of 200 ppb, which corresponds to the human olfactory threshold, using standard gas. The hydrogen sulfide detector tube was used to evaluate oral malodor in 42 outpatients aged 16-80 years, and the results were compared with an organoleptic test (OLT) and volatile sulfur compound (VSC) concentrations measured using a portable sulfide monitor.

Comparing the hydrogen sulfide detector tube with the OLT score, the sensitivity was 0.90 and the specificity was 0.74 for OLT score ≧2.75 (n = 37). For VSC concentrations measured by the sulfide monitor, the sensitivity was 0.85 and the specificity was 1 at ≧300 ppb (n = 41). For OLT score ≧2.75 or VSC ≧300 ppb, which are considered indicators of "clearly noticeable oral malodor," the detector tube showed a sensitivity of 0.84 and a specificity of 1. The diagnostic performance of the detector tube decreased when evaluating mouth air rather than standard gas, possibly due to the inhibitory effects of humidity and other gases in mouth air. Although it did not correspond to the olfactory threshold, the detector was highly sensitive and specific for determining the level of "clearly noticeable oral malodor"; it was considered a practical, easy-to-use tool.

The new hydrogen sulfide detector tube, when used in combination with OLT, should be useful for determining "clearly noticeable oral malodor".