The purpose of this study is to daily monitor the discoloration of teeth when participants rinse with a mouth rinse and black tea and to determine the time point when unacceptable discoloration occurs.

Tooth discoloration is a side effect of most mouth rinse solutions. It impairs the aesthetic appearance especially of the front teeth. The aim of this pilot study is to determine a time point when visible discoloration appears in the front teeth. Therefore, participants of this study will rinse twice daily with chlorhexidine mouth rinse for 10 days. To elicit a more pronounced discoloration, participants will rinse with black tea right after the chlorhexidine rinse. Discoloration will be measured daily by discoloration index, by spectrophotometry, and by the use of a digital photo.

Inclusion Criteria:

• persons aged 18 to 30 years
• written informed consent
• healthy participants
• participants who have no or mild gingivitis
• participants who have all incisors and canines in the upper and lower jaw

Exclusion Criteria:

• participants who have severe general diseases
• participants who have allergies against the ingredients of the mouthrinse
• participants who are enrolled in another clinical study
• participants who are not able to oversee the consequences of the study
• female participants who are pregnant or breast feeding
• participants who have impaired compliance
• participants who have moderate or severe gingivitis
• participants who have fillings in the incisors and canines
• participants who smoke