Everyone knows that the cold hurts your teeth. The reasons are many and varied: untreated decay can lead to a hole in a tooth and hypersensitivity to cold, but the latter can also be due to erosion of the gums caused by aging. But some cancer patients treated with chemotherapy also show extreme sensitivity to cold. Sometimes the feeling of cold on the teeth is so painful that they have to stop their treatment. And if the profession advises people suffering from this phenomenon to protect the enamel of their teeth by banning the consumption of acidic foods or drinks and to avoid traumatic brushing with an unsuitable toothbrush, there is still a lack of treatments for inhibit dental pain. However, a new study could be an interesting starting point for a next drug: at the end of March in the journal Science Advances, American researchers explain having discovered that odontoblasts, the cells that form dentin, are also responsible for the painful sensation of cold on the teeth.
In previous research, scientists had already discovered the TRPC5 protein, encoded by the TRPC5 gene, expressed in nerves in many parts of the body. They then noticed that TRPC5 acted as a mediator of pain due to cold. Here, they looked at mice whose molars had been pierced under anesthesia. Rodents with dental lesions showed pain through their behavior: they drank up to 300% more sugar water than others. But, by genetically modifying mice so that they did not have the TRCP5 gene, they found that those with dental injuries behaved as if they had no problem.
“We now have definitive proof that the TRPC5 temperature sensor transmits cold through the odontoblast and triggers activation of nerves, creating pain and hypersensitivity to cold.says pathologist Jochen Lennerz, one of the lead authors of the article and medical director of the Center for Integrated Diagnostics at Massachusetts General Hospital (MGH). This sensitivity to cold could be the body’s way of protecting a damaged tooth from further damage. “
“TRPC5 makes cells more active in the cold”
In response to cold, the TRPC5 protein opens channels in the odontoblast membrane, allowing other molecules like calcium to enter and interact with the cell. If the pulp of the tooth is, for example, inflamed by a deep cavity, the TRCP5 protein will be overabundant, which leads to an increase in electrical signaling via the nerves emerging from the root of the tooth. These signals then reach the brain, where the pain is felt. When the gums retract due to aging, the teeth can become hypersensitive because odontoblasts feel cold in a newly exposed area.
“Most cells and tissues slow down their metabolism in the presence of cold, which is why donor organs are put in ice., comment Jochen Lennerz. But TRPC5 makes cells more active in the cold, and the ability of odontoblasts to sense cold via TRPC5 makes this discovery so exciting. “
The researchers also identified the presence of the TRPC5 protein in extracted human teeth. To do this, they had to decalcify them and put them in epoxy resin before slicing them to identify the TRPC5 channels in the odontoblasts. “Our teeth are not intended to be cut into ultra-thin layers so that they can be studied under a microscope”, explains Lennerz.
The power of clove oil
“This research brings a new function to this cell, which is fascinating from a fundamental science point of view. But we now also know how to interfere with this cold detection function to inhibit dental pain ”, he congratulates himself.
Finally, scientists have also identified a pharmacological target to minimize the sensitivity of teeth to cold: clove oil. Its active agent, eugenol, blocks TRPC5. If the latter has been used for centuries as a remedy for dental pain, especially through toothpaste, the results of this study could lead to more powerful applications to treat teeth hypersensitive to cold. Eugenol could also be used as a systemic treatment in chemotherapy patients with extreme sensitivity to cold. “I can’t wait to see how other researchers apply our results”, concludes Lennerz.
Symptoms of dental hypersensitivity don’t just happen in cold weather. An affected patient may also experience sharp pain when rinsing their mouth, brushing their teeth, or ingesting food that is too hot or too cold. In France, between 15 and 20% of adults suffer from it, mostly women. If we are to believe the studies, the maxillary premolars are more affected, as well as the canines or maxillary molars.
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