Effects of extracts and compounds on oral bacterial attachment. Effect of tea extracts (a) and EGCg and gallic acid (b) on oral bacterial attachment to the HGF-1 gingival cell line (log CFU/cm2, n = 3). Values labeled with the same letter are not significantly different (p > 0.05) among the treatments within a strain. Tukey’s comparisons were conducted separately for each strain. The * symbol indicates that the attachment of Streptococcus salivarius was significantly different from that of Streptococcus mitis (p < 0.05).