Pacific Coast Society of Orthodontists Bulletin Spring 2013 - (Page 29)
3-D Image-Aided Treatment
of Impacted and Transposed Teeth
Presented by Sunil Kapila, DDS, MS, PhD, at the PCSO Annual Session, October 5, 2012.
Summarized by Dr. Douglas Hom, PCSO Bulletin Southern Region Editor.
hat are the benefits,
risks, and limitations of
cone-beam computed tomography (CBCT)? What are the current
protocols for CBCT use and image interpretation? What are the evidence-based
indications for CBCT? And finally, does
3-D imaging help to optimize biomechanics for impacted and transposed teeth? Dr.
Sunil Kapila addressed these questions
and others during his presentation at the
2012 PCSO Annual Session in Monterey, CA.
responsible for reporting any atypical findings
the to patient and if necessary, recommend
or refer for treatment.. Because of the high
volume of data contained in CBCT scans, the
current recommended protocol calls for both
the orthodontist and an oral-maxillofacial radiologist to interpret the 3-D image.
CBCT is not currently accepted by most clinicians for routine orthodontic records usage.
The prevailing emphasis on evidence-based
therapy in orthodontics leads one to question
what is the best evidence-based use for CBCT
today. In what situations will the information
Prior to ordering a CBCT scan, the orthodontist should
gathered from a CBCT scan likely alter the diagnosis
consider a number of issues. What are the benefits, risks,
and/or treatment plan in a significant number of cases?
and limitations of CBCT? The most immediate benefit is
According to Dr. Kapila, the only situation that currently
that CBCT offers an accurate 3-D representation of anaqualifies under this strict definition is the impacted maxiltomic structures without the superimposition of structures
lary canine. However, a continuous flow of research is
seen in traditional 2-D radiographs. In the diagnosis and
clarifying the protocols. Dr. Kapila expects that unerupttreatment planning of certain types of cases, this capabiled teeth, missing teeth, asymmetries, and anterior open
ity offers distinct advantages over 2-D radiographs. These
bite will also be identified as cases that will benefit from
situations include localization of impacted teeth, quanCBCT.
tification of skeletal discrepancies, and analysis of the
Several presented cases demonstrated CBCT usage in
temporomandibular joint and airway.
assessing the positions of maxillary impacted canines in
The two major risks involved with CBCT are higher rarelation to upper lateral incisors. Visualization of addiation dose (compared to 2-D) and the increased chance
ditional features, such as dilacerated canine roots, was
of missing significant findings. Related risks include the
shown. Finally, a case was presented that demonstrated
problem of over-diagnosis or the detection of false posihow CBCT could be used to optimize biomechanics in the
tives. A large-view CBCT scan exposes the patient to two
treatment of an impacted canine. In this case, the crown
to six times the radiation of a normal orthodontic series.
of the impacted canine was directly adjacent to the lateral
In other words, a large-view scan is equivalent to 10 to 35
incisor root. To avoid iatrogenic root damage, the upper
days of background radiation. (Background radiation is
lateral incisor roots were first tipped mesially away from
estimated at 2,400 microsieverts per year.)
the impacted canine. Using the 3-D image, bracket position and direction of force were then determined in order
The volume of data inherent to a 3-D image is expoto optimally erupt the canine. CBCT images can be an exnentially higher than that of a 2-D image. Because of
cellent modality for communication with the oral surgeon
this fact, the skill set for interpreting a 3-D image has
in terms of specific instructions in bracket placement.
been demonstrated to be significantly higher than that
required to interpret a 2-D image. Thus, the orthodontist
As the interpretation and usage of CBCT continues to
must receive adequate training to develop this skill set.
evolve, most certainly many other evidence-based uses
The practitioner who orders a CBCT scan is considered
will become apparent in the near future
2013 • PCSO BULLETIN
Table of Contents for the Digital Edition of Pacific Coast Society of Orthodontists Bulletin Spring 2013
Save a Little and Invest a Lot
Plan for Ongoing Success
AAO Trustee's Report
PCSO at a Glance
Dr. Terry McDonald Interviews Dr. Harry (Hap) Doughterty, Jr.
Case Report Pre-Treatment
Dr. John Ive
3-D Image-Aided Treatment of Impacted and Transposed Teeth
Controversies in Orthodontics
DIY Technology Upgrades on a DIY Budget
Accelerated Osteogenic Orthodontic (AOO) System -- Physiological Benefits and Increased Range of Movement
Case Report Post-Treatment
Pearls from Idaho: Holding 3-3 Retainers While Bonding
Pacific Coast Society of Orthodontists Bulletin Spring 2013