The Impact of Mouthwashes on Oral Microbiome Communities in University Students

The Impact of Mouthwashes on Oral Microbiome Communities in University Students

Alvin Sherman Library

The oral cavity hosts a complex microbial ecosystem, which can be altered due to physical or chemical exposures, such as dental mouthwashes. This study examined the short-term impact of two commonly used Listerine mouthwashes, alcohol-containing and alcohol-free, compared to water (as control) on the oral microbiome and salivary pH in a college student population. Oral swab samples were collected after the oral rinse and salivary pH measurements were obtained to assess immediate biochemical changes. Microbial DNA was extracted and the V4 region of the 16S rRNA gene was amplified using PCR. Sequencing was performed on an Illumina MiSeq platform, producing 3.6 million quality-filtered sequences with an average of 91,000 reads per sample. Demographic and oral health information was collected to account for potential confounding variables such as hygiene habits and recent antibiotic use. The alpha diversity (the number of bacterial types in an individual sample) and beta diversity (the number of bacterial types shared between samples) surprisingly show no significant differences associated with mouthwash type, although several other metadata categories appeared to be significant related to taxa abundance. These findings highlight the sensitivity of the oral microbiome to commonly used oral hygiene practices. This study contributes to a growing body of dental and oral microbiome research by directly comparing alcoholic, non-alcoholic, and water rinses under controlled conditions.