A randomised crossover trial to compare the potential of stannous fluoride and essential oil mouth rinses to induce tooth and tongue staining.

This study compared the staining potential of two experimental amine fluoride/stannous fluoride mouth rinses (A and B), a phenolic/essential oil rinse (C) and a negative control, water, rinse (D). The study was a single centre, randomized, single-blind, four treatment crossover study design among healthy participants. Prior to each study period, participants received a dental prophylaxis. On the Monday of each period, subjects suspended oral hygiene, and under supervision, rinsed with the allocated mouth rinse immediately followed by a warm black tea solution at hourly intervals eight times a day for 4 days. On Friday, the area and intensity of staining on the teeth, the primary outcome measure and dorsum of tongue were assessed. This regimen was repeated for all the three subsequent treatment periods. Rinse B produced less stain than rinse A, but the difference was not significant (p = 0.20). Rinse B produced significantly more stain than rinse C (p < 0.05) and D (p < 0.001). For tongue staining, rinse B produced significantly more staining than D (p < 0.01) but not A or C. Overall, all test rinses produced more staining than placebo with an overall pattern for more staining with stannous formulations. Individuals using stannous or phenolic/essential oil mouth rinse formulations should be advised of the possible staining side effect and that this can be easily removed by a professional dental cleaning.