This is an excerpt from the American edition of The Power of Habit by Charles Duhigg. It talks of a time when daily toothpaste use was considered unnecessary and burdensome and how an advertising executive changed it all.
To sell Pepsodent, then, Hopkins needed a trigger that would justify the toothpaste’s daily use. He sat down with a pile of dental textbooks. “It was dry reading,” he later wrote. “But in the middle of one book I found a reference to the mucin plaques on teeth, which I afterward called ‘the film.’ That gave me an appealing idea. I resolved to advertise this toothpaste as a creator of beauty. To deal with that cloudy film.”
In focusing on tooth film, Hopkins was ignoring the fact that this same film has always covered people’s teeth and hadn’t seemed to bother anyone. The film is a naturally occurring membrane that builds up on teeth regardless of what you eat or how often you brush. People had never paid much attention to it, and there was little reason why they should: You can get rid of the film by eating an apple, running your finger over your teeth, brushing, or vigorously swirling liquid around your mouth. Toothpaste didn’t do anything to help remove the film. In fact, one of the leading dental researchers of the time said that all toothpastes—particularly Pepsodent—were worthless.
The Adsorption of Human Salivary Proteins and Porcine Submaxillary Mucin by Hydroxyapatite
Archives of Oral Biology 12, no. 7 (1967): 815–28; Won-Kyu Park et al.,
Influences of Animal Mucins on Lysozyme Activity in Solution and on Hydroxyapatite Surface,
Archives of Oral Biology 51, no. 10 (2006): 861–69.
Experimental Studies of the Validity of Advertised Claims for Products of Public Importance in Relation to Oral Hygiene or Dental Therapeutics,
Journal of Dental Research 2 (September 1920): 511–29.