A prospective, cross-over, randomized clinical trial will be carried out in triple blind to compare the effect on dental staining of two 0.12% CHX mouthwashes: with or without anti-discoloration system (ADS). Twenty-two healthy subjects will be enrolled. Briefly, the study includes two sequential stages: in the first phase, the "immediate" objective and subjective evaluation of dental discoloration by spectroscopic and questionnaire-based analyses will be recorded, at baselines and after each 21-days-long cycle of mouthwash. A wash-out period between the cycles of 21 days will be performed.