How teeth sense cold temperatures

New research identifies a protein in teeth that senses a biting chill.

Scientists have located a protein that lets teeth sense cold temperatures in a new paper published in Science Advances.

The protein, TRPC5, is an ion channel: a molecular tube that can open and shut, letting ions through that trigger electrical impulses. It appears in several parts of the body – in fact, when researchers from the Howard Hughes Medical Institute (HHMI) in the US began to examine it 15 years ago, they looked at its effect in skin.

“We hit a dead end,” says team member Katharina Zimmermann, now an electrophysiologist in Germany. But she continued to mull the problem over with David Clapham, a neurobiologist at HHMI, and fellow researchers.

“One day, David said,

‘Well, what other tissues in the body sense the cold?’,” says

Zimmerman. They began to investigate teeth.

This new research shows that TRPC5 is present in teeth, and that it connects to the nerves. It appears in cells called odontoblasts, which are normally well protected but can become exposed from tooth decay.

Researchers investigated mice without TRPC5 in their teeth, alongside a control group of mice with teeth treated with a chemical that blocked the protein. In the control mice, an icy solution touching the teeth prompted a nervous response. Another protein, TRPA1, seemed to have an effect as well. In the proteinless mice, there was no response.

This research explains why clove oil may alleviate tooth pain, as it contains a chemical that blocks the TRPC5 protein, preventing it from triggering nerves.

Cross section of a mouse’s molar, showing the coronal pulp (red) in the tooth’s centre and TRPC5 ion channels (green) within odontoblast cells. The cells’ long-haired extensions fill the thin canals in dentin that extend towards the enamel (at base).