Claude Hopkins, an ad executive, almost single handedly created the habit of toothbrushing. His campaigns for Pepsodent turned it into one of the best-known products on earth, with everyone from Shirley Temple to Clark Gable bragging about their ‘Pepsodent smile.’ Before the campaigns appeared, only 7% of Americans had a tube of toothpaste in their medicine chests. A decade later, that number had jumped to 65%.