For many of us, a “clean” mouth is a minty mouth, and globally, mint is the leading flavor of the oral-hygiene industry—but there are a few regional tweaks. The U.S. leans toward a mixture of peppermint and spearmint, while in the U.K. and China, paste is typically spiked with salt, a natural antibacterial and whitener. In India, cardamom—an antioxidant that helps fight odor—is a common ingredient, and further north, in Japan, green tea and elderflower flavors are freshening breath. If you’re looking to branch out, hipster-beloved Italian import Marvis offers a licorice-laced formula, while French company Lebon has evolved flavor profiles of rose–orange blossom and pineapple. Variety, after all, is the spice of life.…