Download New study may change the face of orthodontics - I-Cat

Dr. Juan-Carlos Quintero discusses how 3D imaging is evolving with more applications and lower radiation
C
one beam computed tomography
(CBCT) was first introduced in the
United States in 2001. Since its inception,
CBCT has been slowly gaining acceptance
as the premier diagnostic tool of choice
in just about every specialty in dentistry,
both as a research and clinical tool. Its
advantages over traditional 2D imaging in
orthodontics have been well documented,
and its use in clinical practice varies from no
use at all, to routine use for every patient. A
2011 independent study showed 4/5 of all
orthodontic residency graduate programs
in the U.S. utilize CBCT for specific
applications, and 1/5 of all such programs
use CBCT as a routine radiograph on all
patients.1 That number is likely increasing
and represents a significant trend towards
CBCT replacing panos and cephs in
orthodontics due to lowering dosimetry
levels and continued reductions in pricing.
3D diagnostics is a mental quantum
leap for most orthodontists when faced
with the prospect of transitioning from a
2D to 3D mindset. As a specialty, we’ve
grown so accustomed to asking diagnostic
questions derived from 2D information (i.e.,
cephs, pano, FMX), that our instinct now
is to ask the same 2D questions from 3D
information. We will never be satisfied with
our answers if we continue such mental
trickery because our anatomy is simply
not 2D. For instance, cephalometrically
speaking, is it really appropriate to ask
about lower incisor angulation from a 3D
data set? Which lower incisor are we talking
about (i.e., the right or the left, the central,
or the lateral)? Which mandibular plane
(i.e., the right or the left; which humanly
located anatomic landmarks define our
plane)? First, it is well documented that
Juan-Carlos Quintero, DMD, MS, received his dental
degree from the University of Pittsburgh in Pennsylvania
and his degree in Orthodontics from the University of
California at San Francisco (UCSF). He also holds a
Master of Science degree in Oral Biology. He has served
as national president of the American Association for
Dental Research-SRG, is a faculty member at the L.D.
Pankey Institute, and an attending professor at Miami
Children’s Hospital, Department of Pediatric Dentistry,
as well as immediate past president of the South
Florida Academy of Orthodontists (SFAO). He currently
practices in South Miami, Florida. His academic
interests include applications of 3D craniofacial imaging
and airways in orthodontics.
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Figure 1A: Dynamic digital modeling (DDM) is a product
of CBCT data, producing a single all-inclusive orthodontic
3D digital record. This DDM product is Anatomodel from
Anatomage Corporation
Figure 1B:Traditional plaster study models used in
orthodontics
Figure 1C: Anatomic segmentation from CBCT data is now readily available using third parties, such as Anatomage
Corporation, to perform enhanced orthodontic studies. This presents dentitions with roots within actual jaw structures,
instead of flat plaster bases as used in traditional models with no roots
cephalometrics is fraught with error.
Second, we’ve grown accustomed to
having a set of multiple diagnostic pieces
that geometrically do not correlate well with
each other (i.e., photographs versus 2D
radiographs versus physical models) like
different languages speaking to each other.
CBCT offers a relatively low-risk solution to
these diagnostic and geometric shortfalls.
There are now over 20 CBCT
manufacturers, most offering different
products. The competition has lowered
prices and, more importantly, lowered
dosimetry levels, a major concern and
obstacle for most orthodontists considering
embracing CBCT for their practices. With
the introduction of newer generation
machines such as the i-CAT® FLX
(Imaging Sciences International), whose
independent validation studies recently
showed a ceph-sized scan (16 cm x 13
cm) to deliver less than half the radiation
of a panorex2, it is now foreseeable that
the orthodontic and possibly the pediatric
community will shift toward CBCT as
the routine imaging modality of choice in
everyday practice. The tide seems to be
turning. Will panos, cephs, and periapical
radiographs in orthodontics soon be
considered outdated, even irresponsible
imaging?
Dynamic digital modeling (DDM) is a
Orthodontic practice 41
TECHNOLOGY
New study may change the face of orthodontics
TECHNOLOGY
Figure 2: Dynamic modeling through segmentation allows
for interactive virtual treatment planning. Here teeth can
be colored, labeled, and even moved using proprietary
software from i-CAT and Anatomage Corporation
Figure 3: Software allows for computerized surgical
treatment planning of orthognathic cases and soft tissue
predictions using 3D data acquired from low-dose CBCT
scans
Figure 5. Eruption management in the mixed dentition using 3D imaging is one of the most
exciting applications of new technology in light of the new low-dose i-CAT FLX
product of CBCT data producing a single
all-inclusive orthodontic 3D digital record
(Figures 1A and 1C). Because volumetric
imaging captures information in the form
of voxels, not pixels, this comprehensive
digital data set can produce an array of
useful diagnostic information in the form of
accurate, interactive, segmented anatomy
in 3 dimensions. The i-CAT FLX captures a
ceph-sized 3D scan in 11-18 microsieverts
(data on file with i-CAT). In comparison,
a digital panorex is 15-25 microsieverts.3
It’s all software modeling after that. The
Anatomodel™ (Anatomage Corporation) is
an all-inclusive orthodontic record file made
from DICOM, producing impressionless
digital orthodontic models with segmented
roots, jaws, condyles, bone, and crowns
(Figures 1A, 1C, and 2). Additionally, a
3D photograph is easily produced and
perfectly wrapped over the soft tissue facial
mapping, resulting in perfect correlations of
soft and hard tissue. Much more than just
a pretty picture, once these individualized
pieces of anatomy have been digitally
42 Orthodontic practice
Figure 4: Temporary anchorage devices (TADs) can be
strategically mapped in 3D for ideal placement and best
surgical planning and communication with patients and
specialists
Figure 6A: Airway segmentation and measuring tools allow for orthodontists to treatment plan around the airways and screen for patients at risk for obstructive sleep
apnea
Figure 6B: Multiplanar reconstruction views (MPR) of CBCT data allow orthodontists
to better evaluate the paranasal sinuses and nasal cavity as it potentially affects the
oral cavity
and independently segmented with Tx
STUDIO™ (Imaging Sciences International)
or Invivodental™ (Anatomage Corporation)
software, it is easy to perform virtual
4D treatment planning involving tooth
movements (Figure 2), OMFS movements,
soft tissue predictions (Figure 3),
computerized planning for TAD placement
(Figure 4), eruption management of the
mixed dentition (Figure 5), and airway
management in all patients. Airway
segmentation and measuring tools allow for
orthodontists to treatment plan around the
airways and screen for patients at risk for
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Figure 7. Volume rendering (VR) with airway segmentation using a low-dose scan on a patient. This
example shows what is possible using a ceph-sized (16 cm x 13 cm ) 11 microsievert scan (data on
file with i-CAT)
Figure 8: The future of orthodontics has arrived. A 3D interactive Anatomodel™ with airway information,
created using an 11 microsievert scan. An average digital panorex is 24 microsieverts as per Ludlow,
et al., 2013
obstructive sleep apnea. It is foreseeable
that airway-centered treatment planning
will become standard in orthodontics with
the arrival of low-dose imaging using CBCT
technology (Figures 6A and 6B).
As a patient education tool and
practice management tool, 3D CBCT
is extremely useful. The visual nature of
CBCT, enhanced with dynamic modeling,
makes the information being presented to
patients easier to understand - in particular
the complexities of treatment that often
go missed or misunderstood. CBCT, in
the form of dynamic models helps present
treatment expectations and treatment
limitations. Some legal experts argue that,
from a medical-legal perspective, one is
better off with a CBCT than without one.
Not only does the file serve as an accurate
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treatment record, but can also help reduce
treatment liability and risk of litigation
because to see is to know; to not see is to
guess.
The future has arrived. Last year,
i-CAT released the i-CAT FLX, yet another
improvement in their generation of machines
making cone beam CT technology better
and safer. Using the QuickScan+ setting,
the i-CAT FLX can produce a ceph-sized
(16 cm x 13 cm) extended field of view
volumetric scan at a dosimetry level as
low as half of a panorex. These levels were
recently confirmed though an independent
academic institution-based study by Dr.
John Ludlow at the University of North
Carolina that measured the dosimetry
levels of the new i-CAT FLX machine.2
These findings, recently published in the
American Journal of Orthodontics and
Dentofacial Orthopedics (AJODO), reports
that the i-CAT FLX can produce a 16 cm
x 13 cm extended field of view image
using the QuickScan+ mode at a relatively
low level of 11-18 microseverts according
to lab-controlled phantom studies. To
give you an idea of how low this is, a
digital panorex is about 25 microseverts
in similar studies.3 The implications of
this in orthodontics and even pediatric
dentistry are enormous. There are still
CBCT machines out there that deliver over
500 microsieverts, so clearly, CBCT dose
varies substantially depending on what
machine and what parameters are used.
What’s more, is that dynamic modeling
and anatomical segmentation of airways
and other structures can just as easily be
performed with this new low-dose scan.
Figures 7 and 8 are examples of what is
readily possible today using a combination
of the i-CAT FLX QuickScan+ settings and
the Anatomodel dynamic modeling at 11
microseverts. Will this set a new standard
as an orthodontic diagnostic record? Has
the radiation-overexposure argument now
been suddenly flipped on its back?
One thing is for sure: With extremely
low radiation doses, CBCT scanners, such
as the i-CAT FLX and its QuickScan+
setting now on the market, mark not only
the end of the CBCT-in-orthodontics
controversy, but likely the future death of
panos, cephs, and plaster (Figure 1B). OP
References
1. Smith BR, Park, JH, Cederberg RA. An
evaluation of cone-beam computed tomography
use in postgraduate orthodontic programs in the
United States and Canada. J Dent Educ. 2011
Jan;75(1):98-106.
2. Ludlow, J and Walker, C. Assessment of
phantom dosimetry and image quality of i-CAT
FLX cone-beam computed tomography. Am J
Orthod Dentofacial Orthop. 2013;144:802-17.
3. Ludlow J, Davies-Ludlow L, White S. Patient
risk related to common dental radiographic
examinations. The impact of 2007 International
Commission on Radiological Protection
recommendations regarding dose calculations. J
Am Dent Assoc. 2008; 139;1237-1243.
Orthodontic practice 43
TECHNOLOGY
Since its inception,
CBCT has been slowly gaining
acceptance as the premier
diagnostic tool of choice in just
about every specialty in dentistry,
both as a research and clinical tool.