Sensodyne is a toothpaste

Toothpaste

Toothpaste is a paste or gel dentifrice used with a toothbrush as an accessory to clean and maintain the aesthetics and health of teeth. Toothpaste is used to promote oral hygiene: it serves as an abrasive that aids in removing the dental plaque and food from the teeth, assists in suppressing...

, toothbrush

Toothbrush

The toothbrush is an oral hygiene instrument used to clean the teeth and gums that consists of a head of tightly clustered bristles mounted on a handle, which facilitates the cleansing of hard-to-reach areas of the mouth. Toothpaste, which often contains fluoride, is commonly used in conjunction...

 and mouthwash

Mouthwash

Mouthwash or mouth rinse is a product used to enhance oral hygiene. Some manufacturers of mouthwash claim that antiseptic and anti-plaque mouth rinse kill the bacterial plaque causing cavities, gingivitis, and bad breath. Anti-cavity mouth rinse uses fluoride to protect against tooth decay...

 marketed for individuals with sensitive teeth and/or dentine hypersensitivity

Dentine hypersensitivity

Dentine hypersensitivity is sensation felt when the nerves inside the dentin of the teeth are exposed to the environment. The sensation can range from irritation all the way to intense, shooting pain...

. It is a registered trademark of GlaxoSmithKline

GlaxoSmithKline

GlaxoSmithKline plc is a global pharmaceutical, biologics, vaccines and consumer healthcare company headquartered in London, United Kingdom...

 which acquired it in 2001 in the purchase of Block Drug

Block Drug

Block Drug Company was a pharmaceutical company based in Jersey City, New Jersey, that specialized in dental care products.GlaxoSmithKline purchased the company for $1.24 billion in 2001....

 which developed it.
The root of the tooth, or the dentin

Dentin

Dentine is a calcified tissue of the body, and along with enamel, cementum, and pulp is one of the four major components of teeth. Usually, it is covered by enamel on the crown and cementum on the root and surrounds the entire pulp...

, is made up of microscopic "tubules" or pores. In some people, the root becomes exposed because of gum recession or gingivitis

Gingivitis

Gingivitis is a term used to describe non-destructive periodontal disease. The most common form of gingivitis is in response to bacterial biofilms adherent to tooth surfaces, termed plaque-induced gingivitis, and is the most common form of periodontal disease...

. Because the tubules are porous, hot and cold sensations (from hot or cold foods or drinks) can reach the nerve endings easily; the nerves fire, causing a sensation of pain or sensitivity.

Sensodyne works because the potassium ions and fluoride penetrate the dentinal tubules and depolarize the nerve, which blocks pain transmission. According to Nickolson (2007), “a dentifrice for desensitizing dentinal hypersensitivity needs to be used for at least two weeks to have an effect, and continued use is needed to avoid relapse” (p. 88).

Active ingredients

• Potassium nitrate
  Potassium nitrate
  Potassium nitrate is a chemical compound with the formula KNO3. It is an ionic salt of potassium ions K+ and nitrate ions NO3−.It occurs as a mineral niter and is a natural solid source of nitrogen. Its common names include saltpetre , from medieval Latin sal petræ: "stone salt" or possibly "Salt...
  
   (5%)
• Sodium fluoride
  Sodium fluoride
  Sodium fluoride is an inorganic chemical compound with the formula NaF. A colorless solid, it is a source of the fluoride ion in diverse applications. Sodium fluoride is less expensive and less hygroscopic than the related salt potassium fluoride....
  
   (0.15 W/V Fluoride Ion)
• Strontium chloride
  Strontium chloride
  Strontium chloride is a salt of strontium and chloride. It is a typical salt, forming neutral aqueous solutions. Like all compounds of Sr, this salt emits a bright red colour in a flame; in fact is used as a source of redness in fireworks...
  
   - creates a barrier around the Dentin
  Dentin
  Dentine is a calcified tissue of the body, and along with enamel, cementum, and pulp is one of the four major components of teeth. Usually, it is covered by enamel on the crown and cementum on the root and surrounds the entire pulp...
  
  http://www.sensodyne.co.uk/how_it_works.htm
• Strontium acetate - creates a barrier around the Dentin
  Dentin
  Dentine is a calcified tissue of the body, and along with enamel, cementum, and pulp is one of the four major components of teeth. Usually, it is covered by enamel on the crown and cementum on the root and surrounds the entire pulp...
  
  
• Potassium chloride
  Potassium chloride
  The chemical compound potassium chloride is a metal halide salt composed of potassium and chlorine. In its pure state, it is odorless and has a white or colorless vitreous crystal appearance, with a crystal structure that cleaves easily in three directions. Potassium chloride crystals are...
  
   - nerve calming
• Titanium dioxide
  Titanium dioxide
  Titanium dioxide, also known as titanium oxide or titania, is the naturally occurring oxide of titanium, chemical formula . When used as a pigment, it is called titanium white, Pigment White 6, or CI 77891. Generally it comes in two different forms, rutile and anatase. It has a wide range of...
  
  (0.1%)http://www.msds-gsk.com/consumer/13038002.pdf (References need about: usage, health and safety)

Not all ingredients are present in all products.