Why would cool water help ease teeth pain?

Constriction: Cold causes blood vessel constriction, which in a confined dental pulp, means less pressure. Less pressure on the tooth nerve means less pain.

A Pulp Condition: That requires seeing a dentist to rule out irreversible pulpitis.

Perhaps: If the problem is inflammation, cool water may decrease the pain. The solution is to see your dentist to treat the cause of the pain.