New York,  Ever thought why cold induces tooth pain and hypersensitivity? Researchers have uncovered odontoblasts, the cells that form a tooth's dentin, have a newly discovered function -- sensing cold -- which can trigger pain in teeth.

However, the researchers, including Jochen Lennerz from Massachusetts General Hospital, have also found a way to block the pathway to cold-sensitive teeth.

"We found that odontoblasts, which support the shape of the tooth, are also responsible for sensing cold," said Lennerz.

Teeth that hurt from exposure to cold can occur for many reasons. Many people have experienced intense pain from cold when they have a hole in a tooth from an untreated cavity.

For the study, the team conducted experiments on mice whose molars were drilled under anesthesia.

Mice with dental injuries manifest pain with their behaviour; they drink up to 300 per cent more sugar water than their litter mates without dental injuries, for example.

In previous research, the team of investigators had discovered TRCP5, a protein encoded by the TRCP5 gene that is expressed in nerves in many parts of the body. Their earlier discovery allowed the researchers to zero in on TRCP5 as a mediator of pain from cold.

By studying genetically altered mice that did not have the TRCP5 gene, the researchers found that the mice with injured teeth did not manifest the increased drinking behaviour and behaved like mice without dental injuries.

The research team also identified a pharmacological target for minimising tooth sensitivity to cold. For centuries, oil of cloves has been used as a remedy for tooth pain. The active agent in oil of cloves is eugenol, which happens to block TRCP5.