Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Adverse effects
RCT	40 people	Mean change in tongue discoloration score from baseline (assessed using the Winkel tongue discoloration index [measured in 6 tongue areas; range 0 = no discoloration to 12 = severe discoloration]) 2 weeks +2.8 with mouthwash containing chlorhexidine plus cetylpyridinium chloride plus zinc lactate +0.3 with placebo mouthwash	P <0.002	Effect size not calculated	placebo mouthwash
RCT	40 people	Tooth staining 2 weeks with mouthwash containing chlorhexidine plus cetylpyridinium chloride plus zinc lactate with placebo mouthwash Absolute results not reported	Reported as non-significant P value not reported		Not significant
RCT 4-armed trial	99 people	Adverse effects 4 weeks with mouthwash containing cetylpyridinium chloride with chlorine dioxide plus zinc mouthwash with essential oil mouthwash with placebo mouthwash Absolute results not reported	4 people were excluded or withdrew after randomisation Analysis not by intention-to-treat
RCT 4-armed trial	174 people	Discoloration of at least 1 upper anterior or incisor tooth day 21 8/44 (18%) with amine fluoride/stannous fluoride, zinc lactate, oral malodour counteractives mouthwash 10/44 (23%) with chlorhexidine, cetylpyridinium chloride, and zinc lactate mouthwash 13/44 (30%) with chlorhexidine mouthwash 5/44 (11%) with placebo mouthwash (tap water)	Reported as not significant		Not significant