Raise your hand if you have never experienced, at least once in their life, the pain (excruciating in case of hypersensitivity) caused by an ice cream or ice water on the teeth. It’s a widespread disorder, between 25 and 30% in a population, which can fortunately be handled with relative ease and a high degree of success. Well so far it has not been possible to understand exactly the transmission mechanism of this painful signal. According to a new study published in the journal Science Advances by researchers at Massachusetts General Hospital (MGH), the suspect could be a “thermometer” protein called TRPC5. The protein is found in the odontoblasts inside the teeth, cells that form the dentin shell just below the enamel. “An interesting study. To date, however, the most accredited theory to explain dentinal hypersensitivity is the one proposed by Martin Brannstrom, who predicts that they are the movements of the peritubular fluid that surrounds the odontoblastic processes to evoke pain with cold, acid and hyperosmolar substances “, comments the professor Antonio Carrassi, director of the Complex Operative Unit of Odontostomatology II-Oral Medicine and Pathology and Geriatric Dentistry, Asst Santi Paolo e Carlo of Milan.
The ion channel
The odontoblasts support the shape of the tooth and, as the researchers have now discovered, these cells also act as cold sensors. These sensors particularly abundant in case of caries, are activated in the cold and cause the nerve fibers to send painful impulses to the brain. They can do it because TRPC5 is an ion channel – a gateway that allows the signaling of chemicals, such as calcium, across cell membranes under certain conditions; in this case they respond to the cold. Based on these results, the authors speculate, they could be developed new treatments to relieve tooth pain or hypersensitivity, perhaps administered via chewing gum or strips applied directly to dentin.
A much studied topic in the last two decades
In reality, Professor Carrassi explains «there are no nerve fibers in the dentin, or rather they are not present along the entire thickness of this tissue with a very particular anatomy, but they run alongside the cytoplasmic processes of odontoblasts (the cells that form the dentin and that are inside the pulp chamber), for a small distance. The US study proposes that the odontoblastic processes contained in dentin are the initial site of the transmission of the “cold” sensation through special molecular microthermometers (TPR). The transmission of “hot” – “cold” sensations was a subject particularly studied during the last 20 years also for the close links with the transmission of “pain” ».
Teeth can become sensitive to cold due to a caries, because ofgum erosion due to aging and for many other reasons: it is one of the side effects of a certain type of chemotherapy treatment, which can even keep patients away from taking medications. Researchers suggest that cold sensitivity could be a warning sign for the body which helps prevent further damage to the tooth: odontoblast cells become more active in the cold, a drop in temperature which usually means the tooth is more exposed. «This study attributes a new function to these cells, which is very interesting from the point of view of basic research, but not only: now we also know how to interfere with this function to inhibit dental pain ». explains the pathologist Jochen Lennerz dell’MGH.
In vivo experimentation: the model must be studied in humans
Having previously identified TRPC5 as a potential temperature sensor, i experiments with laboratory mice the team found that those lacking the gene encoding TRPC5 did not react exposure of the teeth to cold in the usual way. Using chemicals to block the ion channels of proteins had the same effect. “We now have definitive proof that the TRCP5 temperature sensor transmits cold through the odontoblasts and causes the nerve fibers to shoot, generating pain and hypersensitivity to cold, ”adds Lennerz. The typology of the in vitro experiment, however, deserves reflection: «It must be said that the experimental model used by the authors is not perfectly compatible with human conditions – Professor Carrassi underlines – given that rodents, like the mice used in the experiment, do not have a dental structure identical to that of non-rodents, such as humans. However, it is a significant breakthrough that clears up in the mouse the pathogenesis of dentinal pain and pain in inflamed pulp tissue. obviously the model should then be studied in humans and the related confirmed results “.
Also explained the use of clove oil as a remedy
With the cold, the TRCP5 protein opens the channels placed on the membrane of the odontoblasts increasing the entry of calcium ions. If the dental pulp is inflamed, for example from a caries, TRCP5 is very abundant and induces a increased electrical activity of the nerves ranging from the roots of the tooth to the brain. Discomfort can also arise when the gums recede, exposing a new area of the tooth. On top of all this, this new study also helps explain Fr.because clove oil has been used for centuries as a treatment of tooth pain: its active ingredient is l’eugenolo, which blocks TRPC5. No wonder people have traditionally used the oil to reduce sensitivity.
March 31, 2021 (change March 31, 2021 | 12:15)