The effect of four mouthrinses on oral malodor

The purpose of the study was to compare the efficacy of four mouthrinses in clinical outcomes of changes in oral malodor measurements in a 4-week, randomized, double-blind, longitudinal clinical trial in adults. The four rinses were coded as Products 1, 2, 3, and 4 so that neither the examiners nor subjects had the knowledge of treatment. Of the four mouthrinses, two were commercially available mouthrinses with essential oils (EO) or chlorine dioxide plus zinc (CD/Zn) as active ingredients (Products 1 and 4), one mouthrinse was a formulation containing cetylpyridinium chloride (Product 2), and one was a placebo (Product 3). A total of 99 subjects who met the study criteria were assigned randomly to one of the four groups. At three separate visits (0, 2, and 4 weeks), subjects received an examination of the oral soft tissues and were assessed for baseline oral malodor by two organoleptic judges and a laboratory instrument that measures oral malodor. Subjects were instructed to use the assigned rinse, and the measurements were performed again after 2 and 4 hours. Throughout the 4-week study period, each subject was asked to use the assigned rinse twice daily per the manufacturer's recommended directions. The results showed that the four mouthrinses reduced oral malodor within 4 hours after a single usage, with Product 2 being the most effective and the placebo being the least effective. Daily use of EO, CD/Zn, and placebo rinses for up to 4 weeks did not reduce oral malodor from week 0 baseline values, and the effects on oral malodor were comparable among these three mouthrinses. Product 2 was the only mouthrinse that reduced oral malodor from baseline values after 2 and 4 weeks of daily use.