Makino S, et al. - Researchers evaluated chewing gum containing sodium metaphosphate (SMP) for its ability to remove coffee stains from enamel in situ. In this double-blind (subjects, evaluators), parallel-group, crossover, randomized clinical trial, 30 healthy adult volunteers held an appliance with a hydroxyapatite (HA) pellet on the lower lingual side of his or her mouth for two hours to allow pellicle formation. They subsequently immersed the appliances in coffee solution at 37°C for 48 hours. Using a spectrophotometer, they measured the color of the HA pellet before and after coffee immersion. Outcomes suggest the possible efficacy of chewing gum containing SMP in removing coffee stains from HA pellets. Thus, they support SMP as a promising agent that should be further explored in tooth-cleaning studies.