Many young kids who use toothpaste more than needed are at an increased risk of dental fluorosis when they get older, warns a new study.

Fluorosis is a condition that affects the teeth caused by overexposure to fluoride during the first eight years of life.

Fluoride is a mineral found in water and soil. More than 70 years ago, scientists discovered that people whose drinking water naturally had more fluoride also had fewer cavities. That led to addition of fluoride to tap water, toothpaste, mouthwash and other products.

However, the study showed that when teeth are forming, too much fluoride can lead to tooth streaking or spottiness or dental fluorosis.

In addition, the study found that although experts recommend no more than a pea-sized amount, about 40 per cent of kids aged three to six used a brush that was full or half-full of toothpaste.

“Fluoride is a wonderful benefit but it needs to be used carefully,” Mary Hayes, pediatric dentist in Chicago was quoted by Daily Mail.

For the study, the researchers from Centers for Disease Control and Prevention included parents of more than 5,000 kids ages three to 15.

Although the researchers did not determine how many kids developed streaked or spotty teeth as a result of using too much toothpaste, they recommended children under three are only supposed to use a smear of toothpaste the size of a grain of rice, reported Daily Mail.

Kids aged three to six should keep it to a pea-sized amount.

Young kids may push for independence in brushing their teeth, but kids’ toothpaste tastes sweet, according to the team.

“You don’t want them eating it like food. We want the parent to be in charge of the toothbrush and the toothpaste,” noted Hayes.