"The theory of cleaning with natural paste is unsupportable because the absence of fluoride makes the substance without a protective effect," says Damien and Masley, a consultant at the British Dental Society.

The brush only delivers important material to the teeth, but the cleaning tool is not enough to remove harmful substances that cause decay.

Although dentists are alerted, some people think detergents are no different and therefore do not care much about the type of paste they buy.

According to commercial estimates, only 5 percent of the putty sold in the US market does not contain fluoride, but it is likely to rise in the coming years.

Experts say that companies selling fluoride-free paste should make it clear to their customers that the product will not protect them from decay and then they can continue to use it or choose another product.