Strontium toothpaste.
An example of the element Strontium

Sensodyne Mint and Sensodyne Original Toothpaste
These Sensodyne products contain Strontium Acetate and Strontium Chloride respectively.

Beneath your tooth enamel is a layer called dentine, made from thousands of microscopic tubes or tubules. When the nerve endings within these tubules are exposed to triggers like cold drinks, you will feel short, sharp pains. Strontium Acetate and Strontium Chloride help block the tubules, preventing the nerve from being stimulated. Every time you brush with a Sensodyne paste containing Strontium Acetate or Strontium Chloride you are building up a barrier to painful stimuli. Always read the label.