Before the invention of toothpaste in its modern form, the ancients formulated their own versions from ingredients such as crushed egg-shells and powdered pumice. It was not until the 1890’s that Colgate introduced the first tube of toothpaste. By the 1950’s, enamel-strengthening fluoride was added to toothpaste as an effective decay-preventing element. Today, whitening toothpastes are slightly more abrasive than regular toothpastes, which, along with ingredients like peroxide, help them more effectively remove stains. In any case, the primary purpose behind tooth-brushing is to remove plaque, which coats teeth on a daily basis. Unless this pale yellow biofilm is removed, it will continue to build up and harden, and acid produced by the colonized bacteria will attack tooth enamel.
P.S. The wavy layer of toothpaste that sits atop toothbrush bristles is known as a “nurdle.”