Medicine: Pulp fixing
Helen Phillips
A trip to the dentist of the future could be a completely
different
experience. At the moment, if you have decayed or damaged
teeth, you'll
end up with a filling – a synthetic plug for the hole. But
the artificial tooth is
on its way. Engineered tissues to replace the lost
functions as well as the
structure of dental pulp are already under development.
Progress is
reported in the latest 'Polymer Edition' of the Journal of
Biomaterials
Science.
Most of the tooth is made of dentin, a hard connective
tissue with no blood
vessels or nerves. It is coated with a tough enamel layer,
and has a pulp
cavity at its centre. The pulp is a much looser connective
tissue, which
carries out all the nutritional, sensory and defensive
functions of the tooth.
It also provides a breeding ground for developing dentin
cells, and can
probably regenerate itself to some extent.
But when there is serious injury to the pulp tissue,
dentists can only offer
root canal treatment, which replaces the damaged pulp with
a synthetic
substitute. But this is no substitute for the nutritional,
sensory or
regenerative qualities of real pulp, and may ultimately
speed the gloomy
prospect of tooth loss. A more life-like replacement for
dental pulp would
be extremely valuable.
Tissue engineering technology has already allowed
development of muscle
tissue, connective tissue, liver tissue and even structural
replicas of arteries
in the laboratory. Why not an artificial tooth?
Kristyn S. Bohl and colleagues from the University of
Michigan in Ann
Arbor, have taken the first bite at this challenge, by
attempting to grow
replacement tissue that could eventually be used to replace
damaged pulp.
They took human fibroblast cells from real dental pulp, by
mashing the pulp
in a variety of nutritional soups, and 'seeded' the cells on a
three-dimensional structural matrix, or 'scaffold' to allow
them to grow.
The idea is that the cells multiply within the scaffold,
but that the matrix
degrades over time, leaving only the natural tissue.
It sounds simple, but there are many combinations of matrix
materials,
shapes, sizes as well as seeding techniques and nutritional
media to try.
Bohl and colleagues tested three sorts of scaffold that
have proven
successful in other situations. They used one made from
polyglycolic acid
(PGA), as well as collagen (the fibrous protein found in
connective tissue
and bone) and a polysaccharide hydrogel known as alginate.
PGA proved the most successful matrix, but to make the most
of its
success, seeding and growth conditions had to be tweaked as
well. The
researchers worked out that they had to grow a fairly high
density of cells
in the matrix right at the start (which required just the
right combination of
chemicals) to make dense new tissue which will form its own
natural
collagen matrix to support itself.
"These studies indicate dental pulp-like tissues can be
engineered, and this
may provide the first step to engineering a complete
tooth," say the
researchers.
© Macmillan Magazines Ltd 1998 - NATURE NEWS SERVICE
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Elaine T. Hunt, Director
Clemson University Laboratory to Advance Industrial Prototyping
206 Fluor Daniel Bldg. Clemson, SC 29643-0925
864-656-0321 (voice) 864-656-4435 (fax)
elaine.hunt@ces.clemson.edu
http://chip.eng.clemson.edu/rp/persall/elaine.html
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