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DNA & Our Teeth

Inheriting our parents “sweet tooth”

Dental decay is the most common chronic disease of childhood. Irish children have particularly high levels of decay. By the age of five, ~50% of children have cavities. Tooth decay is complex and many factors can lead to children developing poor dental health. Amongst those are frequent consumption of sugars, poor brushing/ not flossing, inadequate exposure to fluoride and soft tissue factors such as tongue ties which prevent children from grooming their own teeth properly. Recently research has shown that there are genes which can lead to a higher risk of children developing tooth decay because of how we taste food.

Although many parents of children with dental problems believe they have inherited weak teeth, this is a myth. We can pass on bacteria to children through sharing tooth brushes and cooking utensils, licking soothers and kissing. We also share some dietary habits with our families because of how we have learned to eat socially and in the way we approach food preparation. Whilst you could say we inherit those things, it isn’t true to call them genetic as they are not passed on through our DNA.

There are two rare genetic disorders which are inherited that cause weak teeth but these are very rare. One is affects enamel and the other affects dentine (the softer layer inside enamel). Thankfully these conditions are rarely seen in this population but are seen frequently in cultures where consanguineous (interfamily) marriage is common. This makes the idea of inheriting week teeth very unlikely.

In the 1990s a chemical called PROP (6-n-propylthiouracil) was found to be associated with food preferences in children. Some people inherit a gene which gives them the ability to taste PROP and others do not. So children can be grouped as “tasters” and “non-tasters”. Tasters perceive PROP to be bitter. Children who cannot taste PROP have been shown to eat more sugars or more sweet foods. We would probably describe those people as having a “sweet tooth” and we all know someone like that. Studies have shown that these “non-tasters” have a lot more tooth decay than “tasters”.

One study from Baltimore in the US recently showed that when a group of mothers were tested for the gene to taste PROP, this could be used as a reliable way of predicting if their children would have tooth decay or not. Increasingly direct to consumer genetic tests are becoming available to purchase online. It is now possible to provide a saliva sample for companies to analyse our DNA to assess who is at risk of certain diseases such as cancer or Alzheimer’s. Many readers will have come across the story of Angelina Jolie who tested positive for a gene increasing her risk of breast cancer, which led to her having a double mastectomy. It is interesting that as these genetic tests become more affordable and more available we may be able to learn even more about how we are affected by our genes.

So what does all this prove? Firstly this shows that we inherit dental issues both directly and indirectly. It also shows that if children come from a family where others in the family have cavities, their chance of having tooth decay is higher than for children from decay free households. It indicates that decay is complex and there are many reasons behind the development of tooth decay. When people ask me about the work I do I find there is a tendency to judge parents of children with tooth decay. I hope this article goes some way to explain that the reasons children develop cavities is too complex to look at children’s dental health in that way.

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