A comparison of the inhibiting potential against oral malodor of zinc ions and two antibacterial agents

Zinc ions in aqueous solution inhibit oral malodor by interaction with precursors of the volatile sulfur compounds (VSC), which are amongst known causes of oral malodor. This is furthermore the case with cetylpyridinium (CP) and chlorhexidine (CHX), both presumably operating through an unspecific antibacterial effect. Objective: To compare the anti-oral malodor effect of these agents in terms of duration, and dose/effect relationships. Method: In a clinical study oral malodor was induced in test subjects by mouth rinses with cysteine solutions. The oral VSC response to cysteine rinses, with and without pre-rinses with differing inhibiting agents, was examined. Tested agents were: Zinc acetate (ZnAc)(0.1, 0.3 and 1.0%), CHX-diacetate and CP-chloride (0.025 and 0.2%). Mouth air was analyzed by gas chromatography according to current methodology, and the 1, 2 and 3h values subsequent to a single rinse with each of the different inhibitors were recorded. Results: ZnAc reduced VSC 97-90% after 1h, and 91-37% after 3h dependent upon concentration. 0.2% CP reduced VSC 45% after 1h, and 30% after 3h. 0.025% CP reduced VSC 47% after 1h and only 15% after 3h. 0.2% CHX reduced VSC 77% after 1h, 95% after 2h and 96% after 3h. 0.025% CHX reduced VSC 46% after 1h, 40% after 2h and 40% after 3h. Conclusions: Zinc ions had a marked short-term effect that deteriorated rapidly with the lower concentrations. The high concentration had an unpleasant, metallic taste, whereas the lower concentrations were found acceptable. CP showed little enhancement of anti-VSC effect with increasing concentration, and the effect deteriorated rapidly regardless of concentration. The high concentration of CHX showed increasing effect with time whereas the low concentration maintained its effect with time. The low concentration of CHX exhibited an acceptable taste and does not appear to cause dental stain.