Using wasabi to regenerate tooth tissue and treat cold-sensitive teeth: Tokyo Dental College

During the ongoing heatwave, eating ice cream or drinking beer cools the body but can also cause sharp pain in teeth even in those without cavities. There are likely quite a few people who suffer from such tooth sensitivity. Unlike persistent pain from cavities, sensitivity is temporary and may be endured. Tokyo Dental College is working on an attempt to treat this sensitivity pain with wasabi. Through industry-academia collaboration, they discovered that a component in wasabi works on tissue regeneration to prevent tooth sensitivity. Currently, they are conducting a clinical trial with patients at Tokyo Dental College Suidobashi Hospital (Chiyoda City, Tokyo Prefecture), aiming to get approval as a drug if efficacy is confirmed in the trial.

Nerve removal shortens tooth lifespan

So, how does tooth sensitivity pain occur from cold and sweet food and drink, or excessively strong brushing pressure? A research team led by Professor Yoshiyuki Shibukawa of the Department of Physiology at Tokyo Dental College recently clarified the origin and mechanism of dentinal pain from sensitivity to cold."

Teeth have a layered structure of enamel and dentin, from outside to inside. Enamel is very hard, while dentin is relatively soft. Beneath the dentin lies a tissue called the dental pulp, which has many nerves and blood vessels. Generally, in cavities in children and adults, bacterial infection spreads from the enamel. In the early stages, treatment rarely causes pain and only requires a small filling.

However, as a cavity grows, it will require extensive treatment, such as a larger crown covering the tooth, removal of nerves and surrounding tissues, or even root canal treatment.

Nerve removal for treatment is said to shorten the lifespan of the tooth due to not only the loss of blood flow but also the loss of tissue that maintains tooth homeostasis. In this era of longevity, "preserving teeth longer" leads to extending the healthy life expectancy. Particularly, back teeth may often be lost before their lifespan due to greater biting forces they endure. However, nothing can truly replace a natural tooth. That is why dentists try to preserve the tooth's pulp whenever possible.

Eating habits and strong brushing pressure cause pain

Dentinal pain is associated with the tooth pain from sensitivity to cold. Frequent consumption of acidic foods, such as wine and other alcoholic beverages, soft drinks, and Lactobacillus drinks slightly dissolve the tooth surface. These eating habits in combination with strong brushing pressure wear down the tooth surface to expose the dentin. Exposed dentin feels pain.

The dentin is rich in small tunnel-like vessels. When the dentin meets a stimulus, fluid inside it moves through them. This fluid movement acts as a stimulus to dentin-producing odontoblasts, which in turn release neurotransmitters such as adenosine triphosphate (ATP) and glutamate into the dental nerve cells, causing dentinal pain.

Common treatments for dentinal pain include physical filling with resin by a dentist and medicinal coating of the dentin surface. However, coating at improper tooth alignment may sometimes come off.

Sushi chef's network of connections with wasabi manufacturers: Here you are!

Shibukawa has been focusing on "possible pain suppression by dentin regeneration" and searching for substances that directly act on odontoblasts.

In another study, Shibukawa and his colleagues revealed that a sensor protein called TRP (trip) A1 is expressed in odontoblasts and involved in dentin formation. Among TRP channels, the TRPA1 channel acts as a sensor that perceives the spiciness of wasabi. The discovery of TRP channels won the Nobel Prize in Physiology or Medicine in 2021. The TRP channels are abundant in nerve cells distributed in the skin and oral mucosa, and functions to perceive stimuli, including not only wasabi but also mint, chili, heat, and cold. Shibukawa thinking, "Wasabi might help generate dentin," went to a sushi restaurant in Tokyo Kanda for dinner and asked the owner, "Do you know any wasabi-related companies?"

The next morning, the owner headed to Toyosu Market and explained the situation to a well-established vegetable and fruit wholesaler. The wholesaler directly contacted a person at a wasabi manufacturer. At 7:30 am, Shibukawa received a call from Isao Okunishi of Kinjirushi (Nagoya), a wasabi trading company, and learned that 6-MSITC contained in Japanese Wasabi has various effects. Industry-academia collaborative research began then and there. The company has named this component hexalaphane and registered it as a trademark.

Elucidation of a mechanism of promoting dentin regeneration

In this study, the research group of Shibukawa obtained reagents for synthesis of 6-MSITC, synthesized eight derivatives, and examined their effects on tooth calcification by odontoblasts from various aspects. Calcification is a very important process for tooth development and regeneration, with calcium and phosphate ions being particularly important for tooth calcification.

They found that 6-MSITC and one of the derivatives, 6-MSFITC, particularly promoted calcification. When they shaved a part of a rat tooth and treated the dentine directly with 6-MSITC, dentin regenerated. They found that this phenomenon is a new mechanism not dependent on TRPA1.

They also found that 6-MSITC activates ion transport in odontoblasts. It induces exchange transport of bicarbonate, hydrogen, and sodium ions within the cell, ultimately pumping calcium ions out of the cell, where bicarbonate ions are abundant. This triggers calcification, resulting in dentin regeneration.

Chewing gum with wasabi component makes you "love cold food and drink"

Shibukawa has conducted a clinical study at Suidobashi Hospital, providing 6-MSITC containing gum to people who answered they "avoid eating cold foods. The idea behind that was to reduce tooth pain by regenerating dentin and protecting teeth. However, this gum does not produce the sharp, nose-tingling sensation associated with wasabi.

The study results showed some effect, with some people answered that they "started liking cold food and drink." In the future, they plan to conduct such study with more people and determine the efficacy. Shibukawa said, "In the future, we want to develop a safer, more reliable and potent tooth regenerating agent that replaces drugs currently used in dental treatment."

However, rather than taking action after you feel tooth pain, it's better to make an effort to maintain a diet that is gentle on teeth and gums from a preventive perspective. When asked about the key points, Shibukawa said, "Do not drink beer, wine, sports drink, black vinegar, or Lactobacillus drink before bed. Drinking these acidic drinks before bed will leave a small amount in your gum pockets. That will dissolve your teeth while you sleep, causing dentinal pain."

We should make a habit of rinsing your mouth and brushing your teeth not only before bed but also after meals. In addition to diet, it is important to avoid too much pressure during brushing, and to visit a dentist for treatment of improper tooth alignment and mismatched filling or crown if you notice any abnormality in your teeth. These should prevent dentinal pain.

Summer is in full swing. It is the season we enjoy cold food and drink. If you experience sharp tooth pain, you would be better off getting treated by a dentist. So, let's eat delicious food without worrying and get through these hot days.