UBC Reports | Vol. 48 | No. 5 | Mar.
Researcher searches nature for better human implants
Shells, teeth may hold clues for hip, joint replacements
by Michelle Cook staff writer
From heart valves to teeth, replacing faulty body parts with artificial
implants is becoming increasingly common. In Canada alone, there
are now 37,000 hip and knee joint replacements performed annually.
The problem is that many of the clinically engineered materials
-- called biomaterials -- used to replace or repair living tissues
have a limited lifespan and will need to be replaced eventually.
It's a costly and painful prospect that UBC researcher Rizhi Wang
says we can avoid by designing biomaterials that will last longer
and function better in our bodies. And he says we need only look
to nature for some engineering inspiration.
"You can always find some model in nature that is very close to
what you are working on and in this you can find ideas and tricks
to use in design solutions," says Wang, an assistant professor in
the Dept. of Metals and Materials Engineering.
He calls his field of research "bio-inspired materials design
and processing" because, he explains, he isn't trying to duplicate
materials found in nature. He is looking for good examples of natural
design interfaces that he can incorporate into the design of materials
processed in the lab like plastic, polymer and titanium.
Wang's research focus is strengthening the gap, or interface,
between an implant and the bone surrounding it with the goal of
encouraging tissues to regenerate. Currently, most implants are
made of titanium with a polymer cement or ceramic coating that may
disintegrate in the body, causing the implant to loosen.
In his search for more bone-friendly materials, Wang has studied
the teeth of horses, cows, alligators and even sea urchins, to examine
their different surface structures and how effectively these act
as an interface. He's also explored the pearl oyster's ability to
produce a strong protective nacreous layer, the material responsible
for creating a lustrous pearl.
Shiny, brittle human teeth have also yielded up some valuable
lessons for Wang. He discovered that although a tooth's surface
is covered in cracks, it is still able to function because of a
thin, soft area between the tooth's hard, outer shell of enamel
and inner core of dentin. Called the enamel/dentin junction, it
performs much like a bumper for cracks.
In addition to continuing his studies on the interfaces found
in mammal and human teeth and other biological systems, Wang hopes
to gain a better understanding of how and why bones and teeth become
deformed or fracture by examining them on a nanoscale. He will also
conduct research on how surface patterns can help improve the fit
between biomaterials and bone and teeth.