Pacific Coast Society of Orthodontists Bulletin Spring 2022 - 29

People in Orthodontics
Faculty Files
Accidental Discoveries and Clinical
Implementations of Therapeutic
Ultrasound in Orthodontics
Dr. El-Bialy is a Professor of Orthodontics at the University
of Alberta, Canada. Among other areas, his interest is in
therapeutic ultrasound use in orthodontics. While this
technology is not widely in-use and recognizing additional
studies are needed, Dr. El-Bialy introduces the concept
of this technology in this article through describing his
thesis research journey.
Dr. Kathryn Preston
Los Angeles, CA
PCSO Bulletin Section Editor
Common orthodontic treatment challenges include
orthodontically induced tooth root resorption (OITRR),
unexpectedly/undesired long treatment time, and
mandibular growth deficiency, among others. For
decades, many causes have contributed to OITRR,
including extended treatment time.
Dr. Tarek El-Bialy
Edmonton, Canada
I encountered several interesting findings during my
research for my PhD thesis in bioengineering at the
University of Illinois at Chicago, College of Engineering
(2001). While studying the possible effects of therapeutic
low-intensity pulsed ultrasound (LIPUS) on bone
formation during mandibular distraction osteogenesis
in rabbits,1
I discovered that applying LIPUS to one side
of the resected rabbit mandible and incisors led to
accelerated eruption of the ipsilateral lower incisor and
formation of new dental tissues (e.g., dentine, cementum,
and periodontal ligament) at the distraction site.2
At the time, I called it distraction dentogenesis; however,
my supervisor said this term was yet to be proven in
higher animals or humans to be considered a new
terminology. So, we instead described the observation
in the long title of the published manuscript.2
This was
my first accidental discovery and proved to be the
foundation for my future research.
The next logical step to assess whether LIPUS would
repair OITRR was to perform an experiment in higher
animals or conduct a pilot study in humans, which
was performed and published3
in the American Journal
of Orthodontics and Dentofacial Orthopedics just a
few years after the first publication studying rabbits.
Although this published pilot study in humans was
valuable, it was clear that more randomized, double-blinded
clinical trials were needed to evaluate
the possible repair effect of LIPUS on OITRR due to
standard experimental, precisely calibrated torque
movement in humans. This was successfully achieved
and published recently.4
The exact effect of LIPUS on the periodontal ligament
and alveolar bone was hard to study in humans
because of ethical issues of harvesting alveolar bone
after experimentally moving teeth with or without LIPUS
application. To study these effects, we first looked
at the possible effect on dentoalveolar structures
during an experimental study using mandible slice organ
culture ex vivo.5
In this study, rat mandibles were
Figure 1. Photos of extracted premolars in the clinical trial (Raza et al., 20164
). The premolar in
the first image (left premolar) was the control side, where only the buccal root torque was applied
with no LIPUS. The premolar in the second image (right premolar) was the experimental premolar,
where the buccal root torque and LIPUS were applied to the buccal surface (red arrow). It can be
seen that the palatal root on the experimental premolar and both buccal and palatal roots of the
control premolar are shorter than the buccal root of the experimental premolar (red arrow)
sliced, with each slice containing teeth, periodontal
ligament, and alveolar bone. The slices were exposed
to experimental tooth movement using calibrated
springs that delivered standardized force to simulate
orthodontic force; because these slices and orthodontic
springs were incubated in tissue culture, it is called
ex vivo. This study showed that not only can LIPUS
enhance dental tissue formation (e.g., cementum and
predentine) as a protective measure against OITRR,
but it also can support alveolar bone remodeling
at the compression site, which, theoretically, may
enhance or accelerate orthodontic tooth movement.
To test this hypothesis, we evaluated the possible
effect of LIPUS on OITRR as well as on alveolar bone
Spring 2022 PCSO Bulletin
29

Pacific Coast Society of Orthodontists Bulletin Spring 2022

Table of Contents for the Digital Edition of Pacific Coast Society of Orthodontists Bulletin Spring 2022