You cannot blame a toothache on bad genes

Even though people are born with microbes in their mouth that they inherited from their parents, these bacteria are not associated with toothaches and cavities, a recent study suggests. 

Scientists and dentists have long understood that streptococcus bacteria in the mouth are linked to the formation of cavities. For the current study, researchers examined the so-called oral microbiome, or blend of bacteria, in the mouths of 485 pairs of twins and one set of triplets who were 5 to 11 years old. 

The researchers studied 250 identical twins and 280 fraternal twins. Overall, oral microbiomes were more similar between identical twins than between fraternal twins. This suggests that genetics play a role in the kind of bacteria in the mouth, the researchers conclude. 

“We do indeed inherit parts of our oral microbiome from our parents,” said study co-author Chris Dupont of the J. Craig Venter Institute in La Jolla, California. 

Older children in the study had fewer inherited strains of bacteria and more types of bacteria that are associated with what we eat, researchers report in Cell Host and Microbe. 

“Cavities are formed when specific microbes in your mouth degrade sugar, producing acid as a byproduct, which then dissolves our teeth,” Dupont said by e-mail. “We found that the microbes you inherit are not associated with cavities.” 

Bacteria that were associated with fewer cavities were in lower abundance in twins who had a lot of added sugar in their food and drinks, the study found. 

In contrast, bacteria that are more common in children who consume a lot of sugar were associated with having more cavities. 

The study was small and did not follow people over time to see how eating habits and hygiene might influence oral bacteria into adulthood. 

While the results offer fresh evidence that genetics can shape the oral microbiome in childhood, the findings also underscore the importance of good eating habits and oral hygiene, said Dr Natalia Chalmers, director of analytics and publication at DentaQuest Institute and a researcher at the University of Maryland School of Dentistry. 

“Parents know the whole idea of nature versus nurture, and many recognise that both the genetics and the environment play a role in how our children mature,” Chalmers, who was not involved in the study, said by e-mail. 

Cavities are preventable, and the best things parents can do for kids is have them brush twice daily with fluoridated toothpaste and see a dentist twice a year, Chalmers advised. 

“The less time we allow food or drink to stay in our mouths without a water rinse or brushing, the less likely we are to develop tooth decay,” Chalmers said. 

Brushing should start as soon as that first baby tooth comes in. 

And, parents also should pay attention to what children eat, avoiding sugary foods and drinks to lower the risk of cavities. 

With extra sweets, kids not only add bad bacteria that causes cavities, they also lose the good bacteria they were born with, Dupont said. 

“Eating lots of sugar speeds up the loss of your heritable microbes,” Dupont said. “Limit sugar consumption.”