 At baseline, level of volatile sulfur compounds VSC in mouth air, Plaque Index and Papillary Bleeding Index will be recorded. Gingivitis subjects will be asked to rinse with Camellia sinensis mouthwash or placebo mouthwash. VSC level will be measured at 30 minutes and 3 hours post-rinsing. For the following 4 weeks, subjects will be rinsed with the assigned mouthwash twice daily after toothbrushing. All parameter will be recorded again at Day 28. 