Breastfeeding has been found to be beneficial for children as the American Academy of Pediatrics also recommend that a mother should breast-feed her new born for at least one year. However, a new study published in journal “Pediatrics” on Friday found that if a child is breast-fed for longer than two years after birth, then there is a higher risk of developing dental cavities.

The study, part of a birth cohort study, was conducted on more than 1,000 children in a southern city of Brazil called Pelotas. At age five, the children were examined for cavities and also the average number of decayed, missing and filled primary tooth surfaces by dentists.

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According to the study, "severe" decay was defined as having at least six cavities. Researchers found that the children who were breast-fed for over 24 months had more than double the risk of developing severe cavities as compared to the kids who had been breast-fed for a year or less.

In the study, researchers also suggested that the high risk of cavities was probably due to older children demanding to be breast-fed and thus making it harder to clean their teeth.

Experts have said that it is extremely important to wipe the baby’s gums after breastfeeding, as breast milk contains high levels of sugar.

"There are some reasons to explain such an association," said Dr. Karen Peres, lead author of the study and associate professor at the University of Adelaide in Australia. "First, children who are exposed to breast-feeding beyond 24 months are usually those breastfed on demand and at night. Second, higher frequency of breastfeeding and nocturnal breastfeeding on demand makes it very difficult to clean teeth in this specific period," CNN quoted Peres as saying.

Results from the study found that, among the children on whom the study was conducted, 23.9 percent had severe cavities in their teeth and 48 percent had at least one tooth surface affected by a cavity. It also said that children who were breast-fed for over 24 months or longer had 2.4 times higher risk of developing severe cavities as compared to the ones who were breast-fed for less than a year.

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However, the study also discovered that breastfeeding between a year and 23 months did not bring the equal amount of risk of cavities in children.

"Prolonged breastfeeding increases the risk of having dental caries. Preventive interventions for dental caries should be established as early as possible because breastfeeding is beneficial for children’s health. Mechanisms underlying this process should be investigated more deeply," the study concluded.

Márcia Vitolo, a professor of health sciences at the Federal University of Health Sciences in Porto Alegre, Brazil, told CNN that prolonged breastfeeding and the amount of sugar content in the milk was able to explain the results of the study. Even though, she was not involved in this study herself, she had conducted similar ones of her own.

"I believe that there is association between breastfeeding and cavities when the environment is unhealthy — like there is a high frequency of breastfeeding during day and night and consumption of sweets and candies," said Vitolo.

Breastfeeding also has its own dental benefits, according to a separate study conducted by Peres in 2015. She found that kids were 72 percent less probable to have crooked teeth if they were breast-bed exclusively for six months. It can also minimize the risk of a condition called baby bottle tooth decay, which often happens when kids are put to bed with bottles containing sugary drinks or the bottle is used as a pacifier.