The University of Oklahoma College of
Dentistry (OU COD) at the Health Sciences Center in Oklahoma City
is on the forefront of discovering a secret weapon that helps fight the
bacteria rapidly growing near the adhesive layer of a dental restoration.
OUCOD’s Fernando Luis Esteban
Florez, D.D.S., M.S., Ph.D., and Sharukh Khajotia, B.D.S., M.S., Ph.D., started
this journey together in 2012 when Dr. Esteban Florez was first hired as a
postdoc at the OU COD. Dr. Khajotia’s research in dental biomaterials, advanced
surface analysis and materials properties testing and Dr. Esteban Florez’s
background in lasers in dentistry, biophotonics and materials sciences sparked
a conversation that led to the question: What if adhesive resins used in
restorative dentistry could not only bond a filling to the tooth, but also be antibacterial
to fight against bacteria that are constantly trying to attack the tooth? The
solution they proposed for that problem was the utilization of nitrogen-doped
titanium dioxide nanoparticles (N_TiO2).
By definition, a nanoparticle
must have all dimensions smaller than 100 nanometers. “A nanoparticle can be
750 times smaller than the thickness of a human hair,” Dr. Khajotia says. “The
properties of many conventional materials are changed when formed from
nanoparticles because they have a great surface-to-volume ratio when compared
to larger particles.” Their initial plan was based on the incorporation of N_TiO2 from a
manufacturer into a commercial adhesive resin. However, that approach resulted
in higher levels of bacterial attachment and biofilm growth.
Drs. Esteban Florez and
Khajotia went back to the drawing board and determined they needed to
synthesize higher-quality nanoparticles and make them functional within dental
polymers. Toward this end, they established a collaboration with Adam
Rondinone, Ph.D., a scientist from the Center for Nanophase and Materials
Sciences (CNMS) at the Oak Ridge National Laboratory (ORNL) in Oak Ridge, TN.
This multidisciplinary team
started to fabricate N_TiO2 using robust synthesis
processes based on solvothermal reactions. Unlike other adhesive resins, the
materials developed display antibacterial properties that are enhanced by
on-demand light irradiation.
research is promising, and the team is hopeful that it will one day be
translated into practice. For now, it has led to other in vitro
findings, such as the nanoparticles’ ability to precipitate crystals containing
high concentrations of phosphorous and calcium from saliva-like solutions.
investigated the nanoparticles using cutting-edge scientific technologies
available at ORNL, including time-of-flight secondary ion spectrometry
(ToF-SIMS), small-angle x-ray spectroscopy (SAXS), small-angle neutron
scattering (SANS) and advanced microscopies. “Using neutron scattering, we can understand how well the nanoparticles
are dispersed, how they are impacting polymer chains, and what types of
interfaces are being established between the polymer and nanoparticles,” Dr.
the research team holds two patents, one for the development of adhesive resins
containing either doped or co-doped TiO2 nanoparticles, and the
other for the nanoparticles’ surface modification. Current research is ongoing
into functionalizing the nanoparticles in areas other than dentistry, including
antibacterial coatings for the control of cross-contamination in hospitals.
of Caroline Rykard, Media Relations Specialist, OU Medicine | Marketing
Published on Oct. 9, 2019