Teething problems brushed aside by rival firms

A brace of toothbrush companies are to launch an all-out assault on tooth hygiene, involving not just brushing but also sound waves and ultrasonic sound.

Sonic toothbrushes, such as the Sonicare, which moves the toothbrush head back and forth 31,000 times a minute (compared to the 2,000 to 6,000 of a typical electric toothbrush), have been on sale since 1996. The ultrasonic toothbrush, called the Ultrasonex, looks like any other electric one. But Robert Bock, its inventor, said thatit could be made to work for cleaning too.

"The brush vibrates at 1.6 megahertz – that's more than a million times a second – which loosens the bacteria and the plaque that build up in a film on your teeth," he said yesterday. The brush still has bristles, which are needed to remove the debris left from cleaning. But Mr Bock insists that the ultrasound does not harm the teeth or gums themselves.

The chains of bacteria that build up into plaque are literally shaken apart, he said. The tooth enamel would not be affected. Pifco, which is marketing it in the UK, insisted that "trials in the US have proven that the Ultrasonex outperforms every rival brush, removing 97 per cent of all daily plaque build up."

However, a study in 1997 by the Family Dental Practice of Roseville, which compared the Ultrasonex with the Sonicare and other electronic toothbrushes, noted that there was not enough proof of this.