Desensitising toothpastes

Revealing the mechanism behind sensitive tooth pain has helped leading brands develop better desensitising toothpastes that provide relief for pain sufferers.

It has been estimated that up to 57 per cent of dental patients suffer from sensitive teeth – pain that’s usually associated with eating or drinking hot or cold food and beverages.

The pain is caused when nerves in the teeth are stimulated by the movement of fluids through the microscopic tubules found in dentine, which is the porous, but hard, middle layer between the inner pulp and the outer enamel of teeth.

Though this mechanism behind sensitive teeth was proposed back in the 1960s, methods sensitive enough to put the hypothesis to the test didn’t exist until the early 2000s.

Bruce Matthews, a Senior Research Fellow and Emeritus Professor in the University of Bristol’s School of Physiology and Pharmacology, and his colleagues, developed novel experimental techniques to measure the fluid flow through dentine and correlate this with the firing of the sensory nerves.

In 2007, they provided the first direct evidence that the fluid flow in the dentinal tubules was responsible for the pain associated with sensitive teeth in humans.

At that time, a number of desensitising toothpastes were on the market that used high concentrations of potassium salts, which were thought to reduce the sensitivity of the nerve endings in dentine.

But Matthews' experiments showed that the potassium salts didn’t have any effect on the nerve response nor on the pain experienced by people. The toothpastes were having no more than a placebo effect.

In 2009, however, a new generation of desensitising toothpastes was introduced into the market.

These toothpastes contained compounds that formed plugs to block the dentinal tubules. This stopped the movement of fluid through the tubules and prevented stimulation of the nerves.

This new generation of toothpastes were targeting the mechanism identified by Matthews and his colleagues, and clinical trials showed they were significantly reducing the pain experienced by people with sensitive teeth – up to a 266% improvement for some patients after four weeks.

Colgate’s Sensitive Pro-Relief and GSK’s Sensodyne Rapid Relief, are two leading brands that target the dentinal tubules.

In 2011, Colgate credited its line of sensitive toothpastes for its improved market share in North America and its expansion into European, South Pacific, Greater Asia and African markets.

In 2013, GSK won product of the year for its latest desensitising product, Sensodyne Repair & Protect. Matthews’ research has underpinned the development of these products, which are sold globally.

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