CONTACT: GARY GALLUZZO
300 Plaza Centre One
Iowa City IA 52242
(319) 384-0009; fax (319) 384-0024
Release: April 15, 2002
UI researchers examine structure of dental fillings, other materials
you've ever wanted to examine the structure of an opaque object -- for example,
a dental filling or porcelain vase -- you may be interested in research conducted
by University of Iowa engineering and dentistry professors at the Iowa Advanced
Technology Laboratories (IATL) Building.
Julie L.P. Jessop, assistant professor of chemical and biochemical engineering
in the University of Iowa College of Engineering, and Steve Armstrong, assistant
professor of operative dentistry in the College of Dentistry, are investigating
changes in the chemical makeup of dental restoration components, including
fillings. They do this by cutting filled tooth samples into segments and scanning
the length of the sample to identify regions of change in the tooth dentin,
the filling composite, and the interface between the two. Their research,
however, is as much concerned with testing the device used to examine the
materials as it is with the materials themselves. In particular, their research
involves an extremely powerful and versatile new instrument -- a HoloLab 5000R
Modular Research Spectrometer -- recently put into use at the UI's Optical
Science and Technology Center (OSTC).
Jessop, who has received a prestigious National Science Foundation (NSF)
Faculty Early Career Development (CAREER) Award, conducts research into photopolymerization,
a light-based process widely used in the film, coating and ink industries,
that is finding new uses in the biomedical, communications, automotive and
aerospace fields. She says that she plans to use the spectrometer's ability
to see below the surface of thin films and coatings.
"This technique, known as confocal microscopy, allows nondestructive
depth profiling of samples," she says. She explains that a laser creates
a Raman scattered light effect in a sample volume. The scattered light is
separated at the collection pinhole, with only the light from the plane of
focus proceeding through to the detector. The technique can help determine
the curing rate of a polymer or the structure of a hybrid polymer as a function
of sample depth.
She adds that the device is modular, meaning that it can be upgraded for
use in other novel research activities. For example, Mark Arnold, OSTC director
and chemistry professor in the College of Liberal Arts and Sciences, plans
to use the spectrometer to determine the concentrations of chemicals in the
blood. His research, in part, involves the development of a non-invasive monitor
for use in treating juvenile diabetes.
In addition, she is working with a UI chemistry researcher to use the Raman
spectrometer to look at films he has fabricated in his laboratory and to determine
the state of the carbon in them. A company interested in using the Raman microscope
to identify imperfections in fiber optic photopolymer coatings also has contacted
Jessop's start-up laboratory funds, the OSTC, the College of Engineering
and the Office of the Vice President for Research provided funding for the
$140,000 spectrometer, manufactured by Kaiser Optical Systems, Inc., a subsidiary
of Rockwell Collins Corporation.