Pacific Coast Society of Orthodontists Bulletin Winter 2014 - (Page 47)
CLINICAL APPLICATIONS of TADs
and OUTCOME EVALUATIONS
with 3-D CBCT SUPERIMPOSITION
Presented by Dr. Jae Hyun Park at the PCSO & WIOC Joint Meeting, October 5, 2014.
3-D SUPERIMPOSITION TECHNIQUES
raditionally, the superimposition of serial,
two-dimensional, lateral cephalograms has been
used for the evaluation of growth and treatment
effects. Nowadays, the superimposition of cone-beam
computed tomography (CBCT) images has become an
important tool for three-dimensional (3-D) assessment of
changes with growth or treatment. However, the assessment of changes with 3-D image superimposition poses
many challenges, including accuracy and reproducibility. Various methods for the reconstruction of 3-D CBCT
images have been used in diagnosis, treatment planning,
and simulation. In this presentation, 3-D CBCT superimposition techniques, especially the iterative closest point
(ICP) method, were discussed.
To transform digital imaging and communication in
medicine (DICOM) data from the CBCT images into polygon data, five software programs were used: VolumeRugle, MicroAVS, VVD2RGL, Point-Rugle, and 3-D-Rugle.
The ICP method can superimpose precisely with repeatability because numerous corresponding points are used
to compare point-based registrations.1-4 To superimpose
two 3-D images at pre- (T0) and post-treatment (T1), the
ICP method was used (Figure 1). In addition, to super-
impose two separate multi-planar reconstruction (MPR)
images accurately, specific points on the cranial base
were used as the reference points for superimposition
(because the cranial base is not greatly influenced by
growth). As a result, accurate superimposition of two separate MPR images is possible. The combined images were
then cut down an arbitrary plane and divided into two
units. The MPR images, which have excellent dimensional
accuracy, were used to compare the data at T0 and T1.1-4
CLINICAL APPLICATIONS and BIOMECHANICAL CONSIDERATIONS of TADs
The use of temporary anchorage devices (TADs) for
reinforcement of orthodontic anchorage has become
increasingly popular, especially in adult patients who
do not want to wear extraoral anchorage appliances.
TADs are convenient and create good treatment results
without patient cooperation. However, if biomechanical
factors are not considered during treatment with TADs,
they can induce side effects (Figure 2). In the lecture, Dr.
Park presented various cases where TADs were used to
achieve sagittal correction,5-9 and treatment outcomes
were discussed using before and after treatment superimposed 3-D CBCT scans.
A. Five different software programs to transform the DICOM
data from CBCT images into polygon data.
2014 * PCSO BULLETIN
B. The iterative closest point (ICP) method. Cranial base superimposition performed on all areas of the cranial base except the
peripheral growing zone. Merged image of pre- (T0) and posttreatment (T1) CBCT scans, superimposed at the cranial base.
Table of Contents for the Digital Edition of Pacific Coast Society of Orthodontists Bulletin Winter 2014
A Clear Message and a Clear Plan
So Much to Share and Celebrate!
Facebook and Orthodontic Practice Marketing
PCSO At a Glance
Poor Posture = Back and Neck Pain
Resident Spotlight: Roseman University College of Dental Medicine, Postgraduate Orthodontic Program
Younger Member Spotlight: Dr. Mahbod Rashidi
The University of the Pacific’s Arthur A. Dugoni School of Dentistry
Dr. Terry McDonald Interviews Dr. Glenn Sameshima
New Technology for a New Office: Cost-Effective and Space-Saving
Case Report Pre-Treatment
Dr. Frank Beglin, PCSO President 2014-2015
Helping Autistic and Special Needs Children
Organization and Innovation are Intertwined
Patient Service: Thinking Outside the Box
Clinical Applications of TADs and Outcome Evaluations with 3-D CBCT Superimposition
Tips and Tricks from the Trenches
Case Report Post-Treatment
Dr. David Thomas Lawless
Pacific Coast Society of Orthodontists Bulletin Winter 2014