Lured by the prospect of a gleaming smile, consumers are happily paying more than £100 for electric toothbrushes. But some of them are no better at removing plaque and stains than the old-fashioned manual brush, according to the latest dental research.

Expensive gadgets which promise to 'get into the nooks and crannies' between the teeth, so banishing bacteria and protecting against gum disease, have become popular in Britain, with some dentists recommending them to clients.

But an exhaustive review of 42 dental trials, involving 3,800 participants, shows the old-style brush is just as effective.

Only one form of electric brush, known as the 'rotating-oscillating' kind, appears to have a better long-term effect. These brushes, with circular heads, brush in one direction then spin round and brush in the other.

Those which do not appear to be any more successful either go from side to side, or use ultrasonic frequencies for brushing.

Sonic toothbrushes have been heavily marketed in Britain, and Friends star Courteney Cox Arquette is said to have invested in one to keep her smile tip-top.

One problem with the manual method, however, is that people tend to spend only 40 seconds brushing, when two minutes is recommended. The other problem is that many fail to brush along the gum line.

Professor Peter Robinson, of the University of Sheffield, who led the Cochrane Collaboration review, said: 'People with electric toothbrushes that don't have rotating-oscillating heads shouldn't worry, as it won't be doing them any harm. However, it is important that consumers know how well their toothbrush will work before making a choice.'