Lafaurie GI, et al. - The substantivity of Hypochlorous acid (HOCl) mouthwashes compared with chlorhexidine (CHX) rinses and a placebo was evaluated. Compared with a 58% reduction by CHX, HOCl resulted in a 33% reduction in bacterial counts in the saliva after 30 seconds. HOCl has no substantivity, and bacterial counts returned to baseline after 1 hour. Placebo treatment led to the highest plaque count after 7 hours compared with the CHX and HOCl groups, however, the differences were not significant. The highest percentages of unpleasant taste and dryness sensations were noted with HOCl rinsing. Findings thereby indicate that HOCl rinses have an initial effect on bacterial viability in saliva but have no substantivity.