Genes not to blame for toothaches


oral microbiome

A new Australian study has revealed that the condition of your teeth depends more on your diet and oral hygiene habits than on your genes.

A team from the Murdoch Children’s Research Institute (MCRI) examined the role genes and environment play in the composition of the oral microbiome and its role in the formation of tooth decay (cavities).


The research, published this month in Cell Host & Microbe, is the first large study to look at ‘oral microbiome’—the bacteria that live in our mouths.

Although scientists have known for some time that Streptococcus bacteria that live in the mouth are associated with tooth decay, what wasn’t clear was the degree to which the presence and growth of these bacteria were influenced by either genetics or environmental factors, such as the amount of sugar consumed.

To work this out, the researchers took mouth swabs from 205 sets of genetically identical twins and 280 non-identical twins aged between five and 11 years.

This enabled them to pin down differences in the genetic make-up of the oral microbiome of children who were the same age and shared the same environment.

The researchers found that certain bacteria in the mouth are inherited—but these were not the same bacteria that caused tooth decay.

They also found that the inherited bacteria decreased over time, and the bacteria linked to environmental factors increased over time.

Bacteria associated with tooth decay was more commonly found in children who consumed more sugar, and those same children also had less ‘good bacteria’—the bacteria associated with fewer cavities.

“This study shows for the first time that both genes and the environment regulate the bacteria on our teeth and gums, with the effects of environment increasing with age,” co-author and principal MCRI research fellow Dr Saffery said.

“Importantly, the bacteria that protect from the development of tooth decay appear to be reduced with excessive sugar consumption—this has never been seen before.”

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