wonder how they did the matrix?

From: Elaine Hunt (elaine.hunt@ces.clemson.edu)
Date: Mon Aug 24 1998 - 21:28:56 EEST


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
*******************************************************************
Opinions, suggestions, and other controversial matter VOID where prohibited.
******************************************************************
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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