Remember those demonstrations in health class where the instructor would stroke away oh-so-gently at an over-sized pair of false teeth with a toothbrush made for the Jolly Green Giant? The right way to brush, she insisted, was up and down. Specifically, on the lower-jaw teeth we were to brush up and vice versa for the top teeth. We were assured that this north-south technique would dislodge food particles caught between teeth as well as keep them from being jammed up (or down) into the gum line. If you are like most people, though, you never quite trusted that you could do a thorough job without throwing in some vigorous side-to-side motion.

Well, the curious news is your health teacher was mostly right: brushing too hard or side to side can cause damage, especially to the dentine – that hard, calcareous tissue that forms the major portion of a tooth, surrounds the pulp cavity, and is situated beneath the enamel and cementum. These days, the American Dental Association (ADA) recommends brushing up and down for the front and back of the teeth (just like your instructor said) and then brushing in circular motion to clean all the teeth surfaces. To get a clean, clean mouth, though, brushing shouldn’t be restricted to teeth and gums. The ADA advises that the cheeks and tongue should be brushed as well to capture, eviscerate, and expel harmful bacteria from the mouth that can lead to bad breath and even gum disease. It turns out that how we brush does matter a lot!