Hop bract polyphenols reduced three-day dental plaque regrowth

Previous research has shown the inhibitory effects of hop bract polyphenols (HBP) on cariogenic streptococci in vitro, but their effects in humans have not been investigated. This double-blind, crossover clinical study tested the hypothesis that HBP delivered in a mouthrinse suppresses plaque regrowth in humans. Twenty-nine healthy male volunteers had all plaque removed, and refrained from all oral hygiene for 3 days, except for rinsing with a mouthrinse containing 0.1% HBP or a placebo. The results showed that the mean amount of plaque assessed by the Patient Hygiene Performance score after the volunteers used the HBP mouthrinse was significantly less than that after they used the placebo (p < 0.001). The number of mutans streptococci in the plaque samples after volunteers used the HBP mouthrinse was significantly lower than that after they used the placebo (p < 0.05). These findings suggested that HBP, delivered in a mouthrinse, successfully reduced dental plaque regrowth in humans.