Many parents can relate to this twice-daily tug-of-war with their kids: It’s time to tear them away from whatever is absorbing their attention and head off to the bathroom for the toothbrushing tango.

A new study points to another challenge — once kids start brushing on their own, many are using way too much toothpaste.

While fluoride is one of the main reasons for a steady drop in tooth decay and cavities in America, according to the Centers for Disease Control and Prevention, ingesting too much fluoride through toothpaste at a young age can lead to problems such as discoloration or pitting of tooth enamel.

The CDC recommends children start using a fluoride toothpaste at age 2, but only an amount about the size of a grain of rice. Between ages 3 and 6, they can use a pea-sized portion. After age 6, their swallowing reflex should be developed enough to limit them ingesting too much toothpaste.

The study of more than 5,000 children across the U.S. reached across socioeconomic and geographic lines for diversity. The researchers used surveys of parents and caregivers to determine when the children started to brush, the frequency of brushing and the amount of toothpaste they used.

Among the findings were that some children in low-income households or in homes where the parents had less than a high school education started brushing their teeth much later than recommended. Also, they found nearly 80 percent of all parents waited too long to start brushing their baby’s teeth, which the CDC says should begin as soon as the first tooth erupts.

Maybe that helps explain why some of the kids are using such big globs of toothpaste — they’re trying to make up for lost time.