The in vitro anti-bacterial activity of EETC against DPB was evaluated. Disc diffusion assay results showed that EETC effectively suppressed the DPB growth and the anti-bacterial activity of EETC were increased with increasing concentration of extract. This concentration of EETC was not cytotoxic to gingival epithelial cells, gingival fibroblasts and macrophage. The induction of inflammatory factors and proteases that contributed to the inflammatory reaction were also abolished by EETC. These results indicate that EETC could effectively suppress the inflammatory responses induced by plaque bacteria. The collective data indicate that EETC is useful in reducing bacterial plaque accumulation and gingival inflammation, thereby preventing periodontal disease. Since the efficacy and safety of EETC has been established, it can be developed into a mouthwash without added alcohol. Many commercially available mouthwashes contain alcohol, which increases the risk of oral cancers and dry mouth.