A Comparative Study of Xylitol and Licorice Root Extract in Inhibiting Streptococcus mutans Growth

Abstract

Streptococcus mutans is a gram-positive bacterium found to be the main cause of dental caries, a primary health problem that Filipinos currently face. Determined to find an alternative to xylitol, a common ingredient in oral health products, this study tested the hypothesis that licorice root (Glycyrrhiza glabra) extract has a greater inhibitory effect against S. mutans, compared to xylitol. Initially, the growth of the S. mutan bacterial sample obtained from saliva was enhanced using Buffered Peptone Water (BPW). Afterwards, four Mannitol-Salt (MS) agar plates were prepared. Licorice root extract was diluted into concentrations of 10%, 30%, 70%, and 100%, and then tested using the Kirby-Bauer disk diffusion susceptibility test protocol, along with a 100% xylitol solution. The zone of inhibition of each solution was then measured and recorded. Different concentrations of the licorice extract showed to have a direct correlation on the zones of inhibition when applied to the bacteria. Their diameters were 8.33mm, 9.45mm, 10.23mm, and 10.96mm, respectively. On the other hand, the zone of inhibition displayed by the xylitol had a measurement of 10.18mm in diameter.In the final analysis, the results supported the hypothesis, concluding that compared to xylitol, the licorice root extract was more efficient in inhibiting the growth of S. mutans.This suggests the use of licorice root extract as an anti-cariogenic component in oral health products.