GSK is claiming a scientific breakthrough with a new Sensodyne toothpaste it says is the first to repair sensitive teeth by forming a protective "tooth-like" layer.

Traditionally, sensitive care toothpastes had used a potassium formulation to numb pain rather than sealing the exposed parts of teeth that cause it, said Paul Gurnell, Category & E-Commerce Controller GSK Consumer Healthcare UK. But Sensodyne Repair & Protect (rsp: £3.99 for 75ml) uses patented Novamin technology, first developed to stimulate bone regeneration, to build up a mineral layer with repeated use, he said.

The launch is being backed by a £5.9m campaign GSK's biggest oral-care marketing spend to date including a TV ad from 4 April, and is rolling into stores now.

People are increasingly suffering from sensitive teeth as a result of "acid heavy" diets, including fruit juice, coffee and wine, said Gurnell. Manufacturers like GSK were also raising awareness of sensitive teeth, he added.

"You get sensitive teeth when you wear away the enamel and expose the inner dentine, which contains tiny channels leading directly to the nerve. This is the first product to rebuild the layers on your teeth, rather than just treating the symptoms," he said.

Sensitive toothpaste is the fastest-growing sector in the £348.5m toothpaste category, up 11% to £98.7m, while the overall category has grown only 2% in the past year [Nielsen 52w/e 22 January]. Toothpaste has been very promotionally driven and only "genuine" category innovation would drive value, he added.