Fluoride Toothpaste – An Invention of Great Importance for Dental Health

Louise Tottie, European Patent Attorney at Valea, recently published an article on one of the first truly effective fluoride toothpastes invented by the Swedish dentist and university professor Yngve Ericsson. The article was published in Swedish in the Swedish dentistry magazine Tandläkartidningen, 2013, No. 14. An English translation of the article is provided below.

 

Fluoride Toothpaste – An Invention of Great Importance for Dental Health and Swedish Research

The Swedish dentist and university professor Yngve Ericsson made a breakthrough with his fluoride toothpaste that came to contribute to improved dental health as well as support for Swedish research for a long time.

Today most people take good dental health for granted. However, less than a century ago dental caries was a widespread public disease and many people did not have all of their teeth as adults.

In Sweden the climax of caries prevalence ocurred in the 1950s . At that time the majority of the population suffered from caries. However, during World War II an improvement of the dental health situation took place, which could be linked to the limited availability of sugar (sucrose) in Sweden. It had then been known for a long time that sugar is directly related to caries.

Caries was also a widespread public disease abroad. In the United States, one of the most common reasons why young men could not enlist for the First and Second World Wars was that they did not have enough teeth.

It was therefore an important step towards improved dental health when the Swedish dentist and university professor Yngve Ericsson (1912-1990) in the late 1950s invented one of the first truly effective fluoride toothpastes.

 

THE YOUNGEST DENTIST IN SWEDEN

Yngve Ericsson was born in a farmer family on the farm Lilla Skee in Harplinge outside Halmstad. As the eldest son he was expected to take over the farm, but his great talent for studying was discovered early in school and led to a change of plans. After graduating with brilliant marks at Halmstad college, he agreed with his brothers that they would help to take care of the farm while he studied to qualify for a profession that gave a good and steady income. Thereafter, he would help them acquire their own farms. This plan was also realized. He chose the dental profession, which seemed safe considering the dental health situation, and which required less time for studies and hence lower study costs compared to the medical profession.

Yngve Ericsson became Sweden's youngest dentist when he graduated at the age of 21. He then worked for 10 years as a dentist in different parts of Sweden. The damages related to caries were huge so there was plenty of work.

Yngve Ericsson returned to the Dental School in Stockholm, where he later became professor of cariology. In 1949, he presented a doctoral thesis on tooth enamel solubility and and its relation to dental caries. At the end of the thesis it is concluded that fluoride ions have a retarding effect on tooth enamel solubility and deserve closer investigation.

 

THE EFFECT OF FLUORIDE WAS ALREADY KNOWN
However, the beneficial effect of fluoride on dental health  was already known. At the beginning of the 20th century it had been observed in the United States that drinking water containing fluoride had a caries preventive effect. Residents of the city of Colorado Springs, where the drinking water had a naturally high content of fluoride, had significantly fewer tooth cavities caused by caries than residents in the relatively nearby city of Boulder, in which the drinking water was practically devoid of fluoride. Unfortunately, the residents of Colorado Springs often had unsightly stains on their tooth enamel, so-called mottled enamel. Later studies revealed that a low level of fluoride in drinking water gave a good caries preventing effect without leading to mottled enamel. Therefore, several states in the US fluoridated their drinking water, which had a very good effect on dental health.

In Sweden it was also discussed if the drinking water should be fluoridated as a dental health measure. Yngve Ericsson belonged to the proponents of fluoridation of drinking water, whereas the later Nobel laureate Arvid Carlsson strongly objected to this. The proponents of fluoridation of drinking water pointed out that caries prevalence in, for instance, Uppsala, where there is fluoride in the drinking water by natural means, was lower than in Gothenburg that has fluoride deficient drinking water. The opponents argued that fluoridation of drinking water could be seen as a form of forced medication which could cause unwanted effects and therefore was unacceptable.

In order to reduce the occurence of dental caries a number of other measures were undertaken during the latter half of the 20th century in Sweden. Fluoride tablets were given to children whose teeth were being formed and in schools regular rinses of the school children´s teeth with a fluoride containing solution took place during visits of the famous so-called "fluoride ladies ." A slight effect was probably also due to the so-called Saturday sweets system, which meant that the children were allowed to eat sweets only on Saturdays.

 

FLUORIDE TOOTHPASTE HAD TROUBLESOME DRAWBACKS
An alternative way of subjecting teeth to fluoride was adding fluoride to toothpaste. Several toothpastes were developed, but were found to have no clinical effect or had troublesome drawbacks. In certain types of toothpaste, sodium fluoride, NaF, was used as a fluoride source together with chalk (calcium carbonate, CaCO3) as an abrasive. Unfortunately, the combination of sodium fluoride and chalk turned out not to have a good clinical effect, since sodium fluoride and chalk react chemically with each other. Another type of toothpaste instead contained stannous fluoride, SnF2, as a fluoride source, but there were problems with its stability and flavour.

The problem to solve was thus to provide a toothpaste counteracting caries while lacking the above-mentioned disadvantages.

 

YNGVE ERICSSON SOLVED THE PROBLEM

Yngve Ericsson solved this problem by inventing a toothpaste which used the chemical compound sodium monofluorophosphate , Na2PO3F, as fluoride source* together with chalk as an abrasive. Sodium monofluorophosphate turned out not to react chemically with the abrasive chalk and gave a good effect against caries. A patent application directed to this toothpaste was filed in 1959 in Sweden and a patent was later granted in several countries in addition to Sweden, such as the United States.

For a chemist the choice of the chemical compound sodium monofluorophosphate as a fluoride source may seem bold, since this compound has structural similarities to nerve gases. However, this was something that chemists in the field had thought about and data suggest that in the 1950s it was known that sodium monofluorophosphate was not toxic.

However, it turned out that others had been thinking along similar lines. The company Colgate-Palmolive filed a patent application in 1955 directed to a fluoride toothpaste with sodium monofluorophosphate as a fluoride source*. This toothpaste also used chalk as an abrasive, but in a much smaller amount than the toothpaste invented by Yngve Ericsson.

Since Colgate-Palmolive filed their patent application first, the patent offices in Sweden and the U.S. put the processing of Yngve Ericsson´s patent application on hold until the scope of protection of the patent application filed by Colgate- Palmolive Patent had been determined. In the end Colgate-Palmolive obtained patent protection for a toothpaste containing sodium monofluorophosphate together with an abrasive containing only a minor amount of of chalk. Yngve Ericsson obtained patent protection for a toothpaste containing sodium monofluorophosphate and an abrasive containing mainly chalk. Thus, in principle the difference in patent protection was that Yngve Ericsson´s toothpaste contained mainly chalk, whereas the toothpaste of Colgate-Palmolive contained only a minor amount of chalk.

 

ESTABLISHMENT OF A RESEARCH FOUNDATION
Through the so-called teacher's exemption, which means that teachers and researchers at Swedish universities own the rights to the results of their research, Yngve Ericsson owned the right to his fluoride toothpaste invention. Exactly 50 years ago, in 1963, he founded together with his colleague Professor Göran Frostell, a research foundation : The Foundation of Swedish Patent Revenue Fund For Research in Preventive Odontology. Yngve Ericsson assigned his patent application to the Society of Swedish Manufacturers of Fluoride Toothpaste and let the resulting royalty revenues go to the foundation. The revenues from the patent were significant and in the course of time they have accounted for more than 99% of the royalty revenues of the foundation. Thereby, the foundation has been able to provide financial support for scientific research in the part of the dental health field called dental prophylaxis research, which is research directed to preventive care and measures. Yngve Ericsson´s patent expired a long time ago, but the foundation still exists, currently with professor Anders Linde, University of Gothenburg, as chairman.

 

A SELECTION INVENTION WITH COMMERCIAL SUCCESS
Yngve Ericsson´s invention is an example of a so-called selection invention. In a patent context a selection invention is an invention based on making a purposive choice from a larger set. At the time when the invention was made, fluoride toothpaste was already known and the use of sodium monofluorophosphate as a fluoride source* was not novel either. However, the specific composition of Yngve Ericsson's toothpaste was not known and the fluoride toothpaste also had a very good caries preventive effect.

The success with respect to health was accompanied by commercial success. The patent, which prevented others from copying the fluoride toothpaste during the patent term, was therefore of great economic value. Presumably other parameters also contributed to the commercial success. Inter alia, the toothpaste was one of the first really good toothpastes on a large and growing market. The high content of chalk in the toothpaste may also have contributed to keeping manufacturing costs low. Yngve Ericsson´s fluoride toothpaste was ingenious in its simplicity and is together with Per -Ingvar Brånemark´s dental implants one of the most important inventions in the dental field.

It is also worth mentioning that at the time the patent application for the new fluoride toothpaste was filed at the Swedish Patent and Trademark Office neither Yngve Ericsson nor the the collective expertise in the field knew exactly the mechanism of action of fluoride toothpaste . This knowledge came only later. However, patent law does not require an explaination of how an invention works. There is a requirement, though, that the invention should be described in such a way that a skilled person may perform it, and this was done in the case at hand.

 

NOT AN ISOLATED STROKE OF LUCK
Yngve Ericsson's many scientific articles, international prizes and further patents are evidence that his patented fluoride toothpaste was not an isolated stroke of luck. For example, in the early 1950s he invented together with dentist L.E. Stjernström a preparation for use as an oral agent, which was sold for a long time under the name Ascoxal by the pharmaceutical company Astra (now AstraZeneca).

In today's fluoride toothpastes sodium fluoride is used as a fluoride source together with abrasives that are compatible with sodium fluoride, such as silica. These fluoride toothpastes provide a better caries protective effect than the one invented by Yngve Ericsson. This is also the way the patent system is supposed to work. In exchange for describing your invention so that everyone can learn from it and develop it further, the patentee gets a time-limited monopoly for the invention.

The fluoride toothpaste invented by Yngve Ericsson was a big step forward and came to contribute to improved dental health, reduced dental costs and support to research . Yngve Ericsson's example also shows how important it is to have a good education system that is able to discover and encourage academically gifted children from economically less affluent homes for the benefit of the children themselves and society at large. Last but not least, an important reason for the success of the fluoride toothpaste invention was that Yngve Ericsson understood the importance of thinking about patents at an early stage in the development process.

Louise Tottie has a Ph.D. in organic chemistry and is a European Patent Attorney at the intellectual property agency Valea AB. Louise Tottie is also Yngve Ericsson´s granddaughter.