Environment, not genetics, to blame for tooth decay

by | Healthy Living, Kids and Teens Health

What’s a typical trip to the dentist like for you? Some lucky folks get a check-up, a clean and they’re out the door without the need for a jab in the gums and some drilling and filling. For others, each visit to the dentist is accompanied by the creeping dread that while picking away in your mouth they’ll spot a cavity – cue pain for your teeth and for your wallet.

The path to cavities is clear – the more sugar you eat, the more you feed the bacteria in the mouth which produce acid to wear your teeth and cause decay. But there’s also been debate about whether your genes play a role in how susceptible you are to cavities from tooth decay – called dental caries.

To tease out the possibilities, Australian researchers tracked more than 150 twin pairs from before they were born until they were six years old, collecting information about their health, their demographics (things like where they lived and their socio-economic status) and their diet.

When they were six, the researchers did dental examinations to see which of the children had developed cavities, and also found out more about the diet of the children – including, importantly, their sugar intake. About half the twin pairs were dizygotic – that’s non-identical – compared with monozygotic – or identical.

Identical twins also have identical genes (while non-identical twins only share 50 per cent of their genes), so if the cause of the cavities was genetic you’d expect the identical twins to have very similar decay.

When they were six years old, more than 100 children had at least one dental cavity, and 83 of those were advanced cavities, often affecting multiple teeth. But the identical twins weren’t more likely than the non-identical twins to have similar tooth decay, which suggests that environmental factors are most important when it comes to which kids are likely to get tooth decay and which aren’t.


Environment seems to be more important than genetics when it comes to tooth decay, at least in young children. The authors said that a lack of water fluoridation and maternal obesity were some of the environmental factors that influenced whether children developed cavities, possibly as a reflection of the amount of sugar in their diet.