Tetsuo Nakamoto

Tetsuo Nakamoto

I was born as the eldest son in my family. My father was a successful dentist in a medium-sized town in Japan. I assumed automatically, as part of Japanese culture, I would inherit his profession once I grew up. I enrolled in pre-Dental School in Tokyo, in April of 1958. In October of that year, under strange and unusual circumstances, I met a French Canadian Catholic priest on a train while vacationing with friends during a short recess at the university.

After riding the train for several hours, an empty seat suddenly opened in front of me and I sat down. I then realized a priest was sitting next to me. I don’t remember how our conversation started, but when he was getting out at his station, he gave me his card and invited me to visit him in Tokyo.

After returning from vacation I accepted his offer and met him in Tokyo. Unfortunately, he suddenly died 10 months later. However, he had great spiritual influence on me in such a short period of time, in spite of the fact that Japan’s main religion is Buddhism, and that I was not even familiar with the word “Catholic,” at the time. I was eventually baptized as a Catholic on his birthday (September 21) in 1961, to remember him the rest of my life. I learned from him to live sincerely and be honest to myself, no matter the circumstances of my life. I wanted to begin with this story, because without it, my life would probably be entirely different.

After graduating dental school in 1964, my father encouraged me to further my studies in the United States, so that I would be a better and more refined dentist. He advised me that if one can make a fine denture (false teeth), patients will appreciate being able to eat foods they need for a healthy life. I enrolled in the graduate dentistry program at the University of Michigan, and conducted my Master’s thesis entitled “A Laboratory Study of Alginate Impressions.” This was my first experiment, and I realized that I liked the experiment. So with my father’s blessing, I was able to pursue further education.

It took almost 12 years to finish my Ph.D. at MIT, and if I had known that, I may have never started! However, I met wonderful people during those years: at the University of North Dakota, Drs. Russel H. Wilson, and Arthur K. Saiki; at the University of Michigan, Dr. John W. Bean; and at MIT, Dr. Sanford A. Miller. When I got the faculty position at LSU Medical Center (now called LSU Health Sciences Center), my boss was Dr. John Spitzer. Dr. Harvey I. Miller was a wonderful colleague in the physiology department, as well as Dr. Johnny R. Porter in the dental school physiology department. I was very fortunate to meet these people.

When I went to the University of North Dakota, I started reading various articles and became attracted to the neonatal rats model. My mentor was Dr. Wilson, an internist and Ph.D., and while he was not familiar with tooth germ (embryological developing tooth), he did not interfere with any of my ideas. Looking back, I was really fortunate as a graduate student to always be the driver of my own experiments, and to receive that same encouragement from all my various mentors throughout different graduate schools.

Because nutritional effects are magnified during early growing period in neonates, I concentrated on the neonatal rat model at MIT. When I got a degree in Nutritional Biochemistry and Metabolism, I finally realized that this was the area I would focus my work on and enjoy for the rest of my life.

After graduating from MIT, I was appointed as an assistant professor of physiology (tenure track position) at LSU Medical Center at the end of 1978. My lab was located in the newly built dental school. I had to set up my own lab and prepare my own lectures. A couple of years after moving from Boston to New Orleans, I shifted my focus from malnutrition to caffeine, but I do not remember why I made the change.

I decided to study in detail the effect of caffeine on mineralization of the tooth, as I knew from the previous studies that caffeine exposure somehow influenced mineralization on hard tissues. Suckling pups were exposed to caffeine through the maternal milk (caffeine was added to the diet of the lactating dams, and this resulted in caffeine released in the maternal milk). Then, a higher amount of calcium, phosphorus, and magnesium from the enamel surface of the pup’s teeth in the caffeine group, were released more than that of the noncaffeine group upon exposures to acid solution in vitro system. The question is why these phenomena occur. My lab was not equipped to study hydroxylapatite (enamel is made from hydroxylapatite) in detail. So I collaborated with Dr. William Simmons and Mr. Alexander Falster, Department of Geology and Geophysics, University of New Orleans, where both are experts of hydroxylapatite and have the related instruments in their lab.

The caffeine group formed a smaller crystal size compared to the noncaffeine control; therefore, these minerals were dissolved easily from the enamel surface when exposed to the acid solution. Then, we hypothesized that in the same animal model but in later life (caffeine was exposed in early life), if we feed a cariogenic diet (diet which causes dental caries) to these animals, the higher incidence of dental caries in vivo system must occur in the caffeine fed group than that of the noncaffeine group. Our hypothesis was right (this was because small crystal size of the enamel dissolved easily by acid production of the oral bacteria, causing the increased incidence of dental caries).

Then we conducted an in vitro crystal formation study to make sure whether the presence of caffeine produced the smaller crystal size in the lab. At the same time we did another xanthine family (caffeine is from the xanthine family), to see whether the crystal size from another xanthine family has differences, if any. To our surprise, theobromine (3, 7- dimethylxanthine) showed the larger crystal formation compared to caffeine (1, 3, 7-trimethylxanthine). This was a real unexpected finding. Then, if I did the same experiment as that of caffeine, but supplemented with theobromine in the maternal diet, using the suckling rats model (pups took theobromine containing milk from dams), the enamel surface of the teeth of these pups must show less release of calcium, phosphorus, and magnesium upon exposure to acid solution (due to large crystal size formation by theobromine in this group). It turned out that this hypothesis was right.

I knew that theobromine was the only chemical beside fluoride which possibly affects the outcome of dental caries. I brought this finding to the university to encourage them to obtain the patent, but they were not interested. Therefore, we got patents by ourselves. Then, I tried to sell the idea to Japanese and US companies, but none of them showed any interest.

At the end of August 2005, Hurricane Katrina devastated New Orleans. The university closed and temporarily moved to Baton Rouge. One day, the mother of Arman Sadeghpour called me (I knew Arman from his time in high school and as an undergraduate at Tulane when he visited my lab). Now he was a graduate student at Tulane University. She asked me if I would help him with his Ph.D dissertation, as his mentor just left the city due to Katrina and he does not have a mentor to direct his research. I told her that I have patents and I was curious to know the different effects, if any, between theobromine and fluoride on teeth. He agreed to join me on this project for his dissertation.

When we got the data, it showed that theobromine was much more effective than fluoride. The results were also reaffirmed by an independent person for his erosion study. During this time, I met Mr. Joseph Fuselier who was very familiar with many aspects of biotechnology. Because my ideas were rejected by so many, I suggested that we start the company by ourselves. We immediately started raising funds to produce the first fluoride-free toothpaste.

The first production of the toothpaste called “Theodent” took close to 5 years from the beginning of the fundraising. We called it “chocolate toothpaste” as theobromine is the main ingredients of cacao. Louisiana had a special incentive for a tax advantage for those who wanted to invest in new ventures. In order to be a unique toothpaste, we spent a lot of time designing the box and tube. As a result of that, we received a Red Dot Design Award which is the first time a toothpaste box design was ever awarded this honor. The award appeared as a headline on a digital billboard in New York City’s Times Square.

When we started selling Theodent in early 2012, we began to receiving emails from many consumers telling us that it improved hypersensitivity (cold and hot stimulus) on their teeth. Because we did not know this effect, we did a clinical study. In fact, we found that Theodent was much more effective than Sensodyne at eliminating pain within a short period of time and the results were published.

Scientists are unique creatures in that they have a special inspiration and imagination compared to other professions. These advantages should be applied not only to the pursuit of pure academics, but also to commercial industries. We should utilize these talents for scientific advances to create practical benefits for common people. Our future roles as scientists should include more collaboration between academics and industry. Scientists would be good entrepreneurs for the practical advancement and happiness of the general population.

Looking back, I experienced many failures through my life which, I thought, often would end my adventure which come from Japan to the US. However, these failures turned out to be one of the most important turning points in my life, and it had an amazingly positive outcome. Younger generations should never be afraid of future failures in their own life.