Tea extracts differentially inhibit Streptococcus mutans and Streptococcus sobrinus biofilm colonization depending on the steeping temperature

This study aimed to evaluate the effects of tea extracts on oral biofilm colonization depending on steeping temperature. S. mutans and S. sobrinus were cultured and treated with green or black tea extracts prepared under different steeping conditions. Biofilm formation, glucosyltransferase (GTF) levels, bacterial growth, and acidogenicity were evaluated. Biofilms were also assessed by gas chromatography-mass spectrometry and confocal laser scanning microscopy. All extracts with hot steeping showed higher inhibitory effects on biofilm formation and cell viability and lower GTF levels compared with those with cold steeping (p < 0.05). Hot steeping significantly reduced bacterial growth (p < 0.05) and maintained the pH. Catechins were only identified from hot steeping extracts. Within the limits of this study, extracts with cold steeping showed lower inhibitory effects on oral biofilms. The different effects between steeping extracts may be attributed to the difference in catechins released from tea extracts under the different steep conditions.