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Pepsodent is a brand of toothpaste with a minty flavour derived from sassafras. The brand is owned by Unilever, but in 2003 the rights to the brand in the United States and Canada were bought by Church & Dwight.
The history of Pepsodent goes back at least to the 1920s.
It was advertised for its purported properties fighting tooth decay, attributed in advertisements to the supposed ingredient Irium. Irium is another word for sodium lauryl sulfate, an inexpensive ionic surfactant. However, in a 1994 speech, then-FCC chairman Reed Hundt claimed that the "Irium" mentioned in Pepsodent advertisements "didn't exist".
Another ingredient, "I.M.P.", which stood for "Insoluble Meta-Phosphate", was purported to whiten teeth. Its best-known slogan was “You'll wonder where the yellow went / when you brush your teeth with Pepsodent!” British comedian Jasper Carrott referred to the slogan in one of his stand-up routines, saying “On your tongue - that's where the yellow went!”
Pepsodent was a very popular brand before the mid-1950s, but its makers were slow to add fluoride to its formula to counter the rise of other highly promoted brands such as Crest and Gleem toothpaste by Procter & Gamble, and Colgate's eponymous product; sales of Pepsodent plummeted. Today Pepsodent is a “value brand” marketed primarily in discount stores and retails for roughly half the price of similarly-sized tubes of Crest or of Colgate.
In the 1930s a massive animated neon advertising sign, featuring a young girl on a swing, hung on a building in Times Square in New York City. This ad was re-created for the climax of the 2005 film King Kong.
The product was discontinued in South Africa in 1974 but was revived in 1976 with a new ad slogan "Gets Your Teeth Their Whitest" featuring celebrity endorsers Rita Moreno, Steve Lawrence, and others. The popular slogan was also changed in South Africa to "You'll wonder where the dullness went / when you polish your teeth with Pepsodent".
Pepsodent is still sold as a Unilever property in all markets except the United States and Canada. In Vietnam Pepsodent is called P/S.
In popular culture 
Pepsodent sponsored a radio program entitled The Pepsodent Show Starring Bob Hope that began airing in 1938 and ran for approximately 10 years on NBC. The show featured Bob Hope and his cast of regular characters such as Jerry Colonna, Barbara Jo Allen as Vera Vague, Frances Langford, and Skinnay Ennis. Famous Hollywood guest stars such as Cary Grant, Orson Welles, Judy Garland, Bette Davis, Humphrey Bogart, Paulette Goddard, Dorothy Lamour, Rita Hayworth, Penny Singleton, Arthur Lake, Basil Rathbone, Gary Cooper, Veronica Lake, Ginger Rogers, Edward G. Robinson, Hedda Hopper, and many more would be on hand to trade comedic barbs with Hope. The show was the first radio program to broadcast live from the Hollywood Canteen on October 13, 1942, and soon the show was playing live to U.S. troops during World War II, even including some of the soldiers in the show.
Bloody Mary's chewing betel nuts
And she don't use Pepsodent.
You're an old Dutch master, you're Mrs. Astor,
One of the great memories of Pepsodent is from an old Mad Magazine 50 or 60 years ago. It had a cartoon (realistic) of Leonardo da Vinci looking at his easel, sitting in front of the Mona Lisa thinking, "I wonder where the yellow went?" Among the tubes of paint is a tube of Pepsodent.
- Church & Dwight news release, September 10, 2003
- Susan Budavari, Maryadele J. O'Neil, Ann Smith, Patricia E. Heckelman, Joanne F. Kinneary. 1996. The Merck Index, twelfth edition. Merk & Co., Inc.: White house Station, NJ. Page 1478
- Reed E. Hundt (October 13, 1994). Address Before the NAB Radio Show. Retrieved 2007-08-21.
- Time Inc (22 August 1955). LIFE. Time Inc. pp. 1–. ISSN 00243019. Retrieved 18 March 2013.