Spotlight on vitamin D, tooth health

The main source of vitamin D is from exposure of the skin to sunlight. PHOTO: GETTY IMAGES
The main source of vitamin D is from exposure of the skin to sunlight. PHOTO: GETTY IMAGES
Deanna Beckett, a PhD candidate in the University of Otago departments of oral sciences, and women’s and children’s health, recently won the Otago Medical School Research Society’s  annual science-writing essay competition. The contest, which attracted 41 entries,  encourages Otago health science students to communicate with a general readership about their research. Entries came from throughout the university health sciences division and the School of Physical Education, Sport and Exercise Sciences. This is her essay.

The sun brings warmth to a chilly day, growth to our vegetable garden and a glow to our cheeks. While it is recommended that we all ‘‘slip, slop, slap’’ the highest SPF sunblock on our skin for protection, completely hiding from sunshine can result in our bodies missing out on vital vitamin D.

While vitamin D is available in small amounts through some foods that we eat, the main source is through exposure of skin to sunlight. Dunedin is not renowned for its abundance of sunlight hours, and this can be an issue for growing bones because vitamin D helps our body to absorb minerals which are really important for bone health.

But what does this have to do with teeth?

Our teeth are made up of many minerals, such as calcium, phosphorus and fluoride, making them the hardest part of our bodies. This poses the question: if vitamin D deficiency affects bone health, could it affect the health of teeth as well? We know that many children have defects in their teeth that are often seen as discoloured patches, ranging in colour from creamy or white, to yellow or brown. What we do not know, however, is whether this is related to a lack of vitamin D.

Trying to test this theory can be difficult, because to know if vitamin D has affected the forming teeth, we would need a blood test from that time. Baby teeth are developing at the fourth month of pregnancy through to birth, and adult teeth start developing from birth. Not many people know their vitamin D status back when they were babies, and it is not information that is routinely collected.

To really answer the question, we need to have a group of children, born in the same year, for which we have blood samples during pregnancy, at birth and in the first six months of life. We also need these children to now be around 6 years of age, when they are losing their first baby teeth and getting their first adult teeth. Simple, right?

Luckily for us, in 2012, a paediatrician in Dunedin wanted to know if providing breastfeeding mothers with vitamin D tablets would increase the vitamin D levels of their babies. To check this, they looked at the levels of vitamin D in the blood of both mothers and babies during pregnancy, at birth and at six months after birth. The children from this study were 6 in 2018, the perfect time for a dental study, and the birth of my PhD study!

We invited 120 children from the 2012 study to be involved, and 82 of them were happy to participate. These children had a dental assessment where we looked at how well their teeth had formed. In particular, we noted if there were any discoloured or weaker defects on them, and whether the teeth had decayed after coming through into the mouth. The children were also asked if they would like to donate a tooth, when one fell out naturally. In return, they received an official letter from tooth fairy kingdom thanking them for their tooth and $5 from the tooth fairy. Sixty-seven children donated teeth which we then cut in half and examined in the laboratory.

Now that we have collected all this information, our next step is to compare it with the vitamin D levels of the children from back when their teeth were forming.

Why do we care?

If dental defects happen on front teeth, they can be obvious when you smile, and this can make children unhappy. For back teeth, if the enamel is weaker, teeth may chip or break down more easily, making them more prone to tooth decay. Even when there is no tooth decay, these teeth can be very sensitive, meaning that brushing, eating and drinking hot or cold liquids can be painful.

Super-sensitive teeth are also much harder to get numb when dental treatment is needed, a bit of a dilemma, as children with these defects are more prone to dental decay and therefore more likely to need dental treatment. Sometimes the teeth can be so weak, discoloured and broken down, that they need to be taken out entirely.

My hope is that this research will help us determine if defects of the teeth are more common in children who lack vitamin D during pregnancy and early childhood. If this was the case, it would strengthen the evidence base for supplementation of vitamin D during critical life stages such as pregnancy, lactation and early childhood.

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