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True or False? Myths of IU, Fluoride

Joseph C. Muhler and the formula that became Crest toothpaste, Dec. 9, 1952. Photo courtesy of IU Archives.

Time and imagination can bury the truth of a person, place, or event under layers of mythology. By excavating facts from the deep sediment of urban legend and storytelling passed from one generation of IU tour guides to another, this series puts IU myths to the historical test.

We’ve heard it again and again, the legend of the IU researchers who invented fluoride. Some of us have even heard that the royalties from this invention funded the construction of Ballantine Hall. But, is it true?

Strictly speaking, neither legend is true. IU researchers did not invent fluoride. They did, however, invent a formula for fluoridated toothpaste, which was and continues to be a profound global health success. The royalties from the project did not fund the construction of Ballantine Hall, but they did help fund an important IU research institute. Here is the real history.

For thousands of years, human beings have used abrasive pastes to clean their teeth. Ancient cultures in Africa, the Mediterranean, and Asia each have historic examples and recipes for pastes made from abrasives such as pumice or sea shells, mixed with flavorings to freshen breath and binders to hold it all together.

The basic use and function of toothpaste remained unchanged for thousands of years, but by the early 20th century, epidemiological pioneers established there were lower incidences of dental cavities in communities with higher levels of naturally occurring fluoride in their water supply, cluing researchers in to a correlation between fluoride and cavity prevention.

In fact, the first uses of fluoride as a clinical treatment—adding fluoride to public water supplies—attempted to emulate the protection offered by naturally elevated levels of fluoride. Municipal water fluoridation actually preceded fluoride in toothpaste by decades. In 1945, the city of Grand Rapids, Mich., added fluoride to its water supply. Within a decade, the caries rate in the community dropped 60 percent.

The presence of dental caries (cavities) worldwide increased sharply during the Industrial Revolution, with the increased availability of refined sugar and flour, so the study of cavity prevention was increasingly salient for researchers. By the time the U.S. government was drafting soldiers for World War II, the single greatest cause for draft ineligibility was failing to meet the Army’s standard for required minimum number of teeth for an 18-year-old, which was three pairs of incisor teeth and three pairs of masticating teeth … a minimum of 12 teeth remaining at the end of adolescence out of the full set of 32. After the first year of the war, the Army was forced to reduce that requirement because they were failing to meet enlistment targets.

Once academics and toothpaste producers realized that fluoride strengthened tooth enamel, the race was on to isolate and develop a fluoride ion that would be shelf stable and compatible with the abrasives customarily found in marketed toothpaste. The first company that could offer a toothpaste that could be objectively proven to prevent tooth decay would have a monumental market advantage over its competitors.

Indiana University was among the academic institutions in this pursuit. IU professors Drs. Harry Day (biochemistry) and William Nebergall (inorganic chemistry) headed a team out of Bloomington, Ind., investigating possible solutions. It was at this point when Dr. Joseph Muhler, BS’47, DDS’48, a dental researcher at the IU School of Dentistry who had been working on research into the structure of phosphates, discovered a calcium phosphate that successfully bonded with stannous fluoride into a paste that was both abrasive and did not cause the fluoride ions to dissipate over time.

Their research showed that a toothpaste made with fluoride in this fashion didn’t just help prevent demineralization by scrubbing away bacteria and their food source (sugar) from teeth, but it actually rehardened tooth enamel by releasing fluoride ions that convert the calcium mineral apatite, a part of tooth enamel that can be dissolved by mouth acid, into the much stronger mineral fluorapatite. This strengthening process made tooth enamel harder and more resistant to decay.

A prototype toothpaste was ready by 1952, and IU ran clinical trials on almost 2,000 Hoosier adults and children to demonstrate the efficacy of this new type of toothpaste. The university was granted a patent for the compounds and applications, which were then licensed to Procter & Gamble in Cincinnati. P&G released the product as Crest® toothpaste. In 1960, the American Dental Association bestowed Crest with its first-ever Seal of Acceptance, and by the end of the 1960s, Crest held more than 90 percent of the U.S. toothpaste market.

IU continued to receive royalties from P&G for Crest until the patent expired in 1975. Part of those funds were used to establish the Oral Health Research Institute at the IU School of Dentistry in Indianapolis in 1968. The Oral Health Research Institute continues today as a world-renowned oral health product testing laboratory.

The partnership between Procter & Gamble and Indiana University was also an early example of what would eventually be known as the field of University Technology Transfer, which governs the transfer of intellectual property developed in academic institutions for application and monetization by private corporations.

In 1968, the same year IU opened the Oral Health Research Institute, the government introduced its first “Institutional Patent Agreement” to govern the transfer of research intellectual property from nonprofit institutions. The 1980 Bayh-Dole Act, drafted in part by Indiana’s own Senator Birch Bayh, JD’60, LLD’95, still regulates this research patent arena.

While no longer held under patent by IU, the original stannous fluoride formulation continues to be used as the active ingredient in both Crest Pro Health® and Oral-B Pro-Expert toothpastes.  Today, while available with a variety of other fluoride compounds, fluoridated toothpaste is one of the most important tools in the global battle against dental caries, a disease that continues to affect billions worldwide.

This article originally appeared in the August 2018 issue of 200: The IU Bicentennial Magazine, a special six-issue magazine that highlights Bicentennial activities and shares untold stories from the dynamic history of Indiana University. Visit for more Bicentennial information.

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Written By

Terry L. Wilson, Jr.

Terry Wilson, Jr., JD’07, MA’12, is the director of public relations and marketing for the IU School of Dentistry, and a contributor to 200: The IU Bicentennial Magazine.

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