Have you ever had a toothache from drinking something cold? Maryland scientists have finally found the reason behind this painful phenomenon.
“It’s a unique type of pain,” says David Clapham, vice president and chief scientific officer of the Howard Hughes Medical Institute (HHMI). “It’s just unbearable.”
He and an international team of scientists have discovered how teeth can feel cold. They have also discovered the molecular and cellular processes behind why this occurs. The team found that in both mice and humans, dental cells called odontoblasts have cold-sensitive proteins that detect lower temperatures. These cells then send a signal to the brain, alerting it to the painful sensation.
The team published these results on March 26, 2021 in the magazine.
Sensitivity to cold and tooth pain.
Study reveals why popular natural remedy, clove oil, soothes toothache. Clove oil, which dentists have used for centuries, contains a compound that blocks cold-sensitive proteins.
Electrophysiologist Katharina Zimmermann, who led the work at the Friedrich-Alexander University of Erlangen-Nürnberg in Germany, explained why this works. She says that the development of drugs that more specifically target this sensor could eliminate tooth sensitivity to cold. She says this:
“Once you have a molecule to target, there is a possibility of treatment.”
Teeth begin to deteriorate when bacteria and acid erode the enamel, the protective layer that covers the teeth. As the enamel wears down, cavities begin to form. About 2.4 billion people, or about a third of the world’s population, have untreated cavities. This can lead to toothache, which can occur from drinking ice-cold beverages.
Before this study, scientists did not know how teeth detect cold temperatures. However, the scientists speculated on what caused it and came up with a theory.
Inside each tooth, small channels contain fluid that moves when it senses changes in temperature. The scientists proposed that the nerves detect the direction of movement. This then indicates whether a tooth has been exposed to heat or cold, according to some researchers.
“We can’t rule out this theory,” but there was no direct evidence for it, says Clapham, a neurobiologist at HHMI’s Janelia Research Campus.
Find out why cold drinks cause toothache it was a process of elimination
Scientists said fluid movement in teeth and tooth biology are not easy topics to study. Scientists have to cut through enamel, the hardest substance in the body, and an additional layer of tough dentin. This is very difficult to do without crushing the soft pulp, blood vessels, and nerves of the tooth.
Sometimes the whole tooth “just falls apart,” says Zimmermann.
However, Zimmerman, Clapham and their colleagues did not aim to study teeth. They focused primarily on analyzing ion channels, pores in cell membranes that function as molecular gates.
The channels detect signals such as chemical messages or changes in temperature. Then, depending on the signal, they are either hermetically sealed or opened wide to allow the ions to enter the cell. This causes an electrical pulse to move from one cell to another. This sends information quickly and plays a crucial role in the brain, heart, and other tissues.
About 15 years ago, Zimmerman worked as a postdoc in the Clapham lab, where the team made an important discovery. The ion channel called TRPC5 showed extreme sensitivity to cold. However, the team was still unsure where the channel’s cold-sensing ability was on the body.
In the study, they eliminated the skin as a receptor for TRPC5’s ability to feel cold. The team found that mice that did not have the ion channel could still detect cold. They reported these findings in 2011 in the journal..
After that, “we hit a dead end,” says Zimmermann. One day at lunch the team was reviewing the study when they finally had an idea. ” David said, ‘Well, what other tissues in the body feel cold?’ ”Zimmermann recalls. The answer? Teeth.
The experiment that led to the discovery of teeth that detect cold.
Study co-author Jochen Lennerz, a pathologist at Massachusetts General Hospital, examined teeth in adult humans. He found that teeth have TRPC5 and that most of it resides in decayed teeth.
The researchers used mice to test their theory. This experiment showed them that TRPC5 works as a cold sensor. They decided not to open a tooth to examine the cells instead of looking at the entire tooth. They studied the jaw, the teeth, and the nerves within the teeth. The team then recorded neural activity after applying an ice-cold solution to the teeth.
They found that the drop in temperature triggered nerve activity in normal mice, showing that the teeth sensed cold. They did not see this in mice without TRPC5 or in teeth treated with chemicals that blocked it. This showed the team that the ion channel could feel cold, Zimmermann says. Another ion channel the group studied, TRPA1, also appeared to detect cold.
After confirming that TRPC5 could sense cold, they traced its location to a dental cell called odontoblasts. This is found between the pulp of the tooth and the dentin on the teeth. When someone bites into something cold with a tooth exposed to dentin, this sends a pain signal to the brain.
Clapham says that even though many people experience this acute pain, it has not been studied much. Says that while toothache it is not widely recognized in science, “it is important and affects a lot of people.”
Zimmerman says the team’s discovery of why cold sensations cause tooth pain took more than a decade. She says determining the function of specific molecules and cells is not easy.
“And good research can take a long time.”
Final Thoughts: Scientists Finally Found Out Why Cold Foods Or Drinks Cause Tooth Pain
After more than ten years, scientists studying ion channels discovered that TRPC5 detects pain when exposed to cold. This ion channel in tooth cells called odontoblasts reacts strongly to cold sensations and is especially common in cavities. Hopefully this knowledge will lead to better treatments targeting this sensor and eliminate tooth pain resulting from the cold.