Children brush their teeth with so much toothpaste that it is unhealthy, says the Center for Disease Control and Prevention.

A CDC study found that nearly 40% of children ages 3 to 6 use more toothpaste than dentists recommend. The CDC and the American Dental Association recommend that children in this age group do not use more than a quantity of dough the size of a pea. Children under 3 years old should only use a smear, only the size of a grain of rice.

The findings of the CDC published Friday are based on a survey of parents of children aged 3 to 15 years and found that about 60% of children and adolescents aged 3 to 15 years used half or a full load of toothpaste. In children aged 3 to 6 years, approximately 12% used a smear, 49.2% a pea size, 20.6% at a half load and 17.8% at full load.

Brushing with too much toothpaste can damage the enamel, as children could swallow too much fluoride during the development of their teeth, says the CDC. This can cause dental fluorosis, white marks and discoloration of the teeth.

The brushing habits of about 5,100 children were included in the report on the database from 2013 to 2016.

The American Academy of Pediatrics and the CDC recommend that parents start brushing their child's teeth with a toothpaste at the age of 2 years. Brushing with water is recommended as soon as the teeth come in. The CDC survey found that nearly 80% of children began to brush their teeth after a year.

The data used for the analysis was based on the parents' statements. In addition, it is not known whether the toothpaste presented was fluorine or non-fluorine.

More: You probably brush your teeth with feces

More: What would happen if you do not brush your teeth for a year?

Follow Ashley May on Twitter: @AshleyMayTweets