Human
teeth hold vital information about Vitamin D deficiency, a serious but often
hidden condition that can now be identified by a simple dental X-ray, McMaster
anthropologists Lori D'Ortenzio and Megan Brickley have found.
Their
research appears today in the International Journal of Paleopathology.
The
researchers and their colleagues had previously discovered that human teeth
hold a detailed and permanent record of serious Vitamin D deficiency, or
rickets. That record takes the form of microscopic deformities in dentin, the
material that makes up the mass of the tooth, and can be extremely valuable for
understanding precisely when people, even those who lived centuries ago, were
deprived of sunlight, the main source of Vitamin D.
The
record is preserved by enamel, which protects teeth from breaking down, unlike
bones, which are subject to decay.
The
problem with looking for such deformities is that a tooth must be cut open to
read the patterns that form a lifetime's Vitamin D record, and the supply of
post-mortem teeth available for study is limited.
To
avoid wasting precious specimens, the researchers went looking for a way to
isolate teeth for further study. By using X-rays to study the readily
observable shapes of the "pulp horns" -- the dark shadow at the
centre of the image of a tooth -- they found a consistent, recognizable pattern
that could prove helpful not only to their studies of archaeological teeth, but
to living people who may not realize they are suffering from Vitamin D
deficiency.
"We
were looking for a non-destructive method so we wouldn't need to destroy
precious archaeological material to see if there had been a deficiency,"
says D'Ortenzio, a PhD candidate in anthropology and lead author of the paper.
"Now we know which teeth to look at."
The
pulp shape in a healthy person's tooth resembles an arch topped by two cat
ears, while the pulp shape of a person who has had a severe deficiency of
Vitamin D is asymmetrical and constricted, and typically looks like the profile
of a hard-backed chair.
D'Ortenzio
and Brickley's previous research had suggested such a recognizable pattern, and
their examination of both historic and current teeth proved that X-ray images
are consistent and reliable indicators of prior deficiency.
"It
was a real Eureka! It wasn't just that it looked different. It was
different," says Brickley, a Professor of Anthropology who holds the
Canada Research Chair in the Bioarchaeology of Human Disease. "I think
it's really important. It was a piece of work that aimed to look more at past
individuals, but it has the potential to contribute to modern health care as
well."
Since
the consequences of Vitamin D deficiency can be severe - especially in terms of
bone health - knowing who has had a deficiency can help identify people who may
have ongoing issues in time to prevent worse damage, the researchers say. If
regular dental X-rays show a problem, blood tests can confirm whether there is
an ongoing deficiency.
Such
evidence could be particularly valuable in the case of children whose bones are
still growing, the researchers say, and spotting a problem early could head off
future problems with Vitamin-D related bone deficiency.
Knowing more about
ongoing Vitamin D deficiency can also help to determine what is the best
balance between protecting people from harmful UV rays and making sure they get
enough sun to maintain a healthy level of the vital nutrient.
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