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Use of digital models to assess orthodontic treatment progress

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Use of digital models to assess orthodontic treatment progress

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Content 1
USE OF DIGITAL MODELS TO ASSESS ORTHODONTIC TREATMENT PROGRESS

by

Eric Budiman
1
and Christopher R. Myers
2

A Thesis Presented to the
FACULTY OF THE USC GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
MASTER OF SCIENCE
(CRANIOFACIAL BIOLOGY)

May 2015

ERIC BUDIMAN
1
AND CHRISTOPHER R. MYERS
2

2
Table of Contents
Abstract 3
Chapter 1: Digital Models
A. History 4
B. Digital Model Acquisition 5
C. Uses in Dentistry 7
D. Precision and Accuracy 8

Chapter 2: American Board of Orthodontics
A. Final Model Objective Grading System 11
B. Common Errors 12
C. Digital Models for the Objective Grading System 13

Chapter 3: Our Current Study
A. General Overview 14
B. Align Technology iTero Intraoral Scanner 14

Chapter 4: Hypotheses 17
Chapter 5: Methods 18
Chapter 6: Results 21
Chapter 7: Discussion 28
Chapter 8: Conclusions 32
Bibliography 33
List of Tables and Figures 36

3
Abstract. Use of Digital Models to Assess Orthodontic Treatment Progress
Objective: Progress models are commonly made during the detailing and
finishing stages of orthodontic treatment with alginate impressions and plaster.
Three-dimensional intra-oral scanners, such as Align Technology Inc.’s iTero, can
be used in place of traditional models. The objective of this study was to assess
whether the three-dimensional models were useful in visualizing treatment
progress per the American Board of Orthodontics (ABO) final model grading
system. Methods: In this prospective study, 20 patients in the detailing and
finishing stages of orthodontic treatment were scanned using the iTero intra-oral
scanner. 10 ABO certified faculty orthodontists of the University of Southern
California used the three-dimensional model to assess treatment progress and
completed a survey to determine which sections of the final model grading
system were easy or difficult to visualize. Results: Assessing treatment progress
and visualizing tooth alignment (rotation), occlusal contacts, overjet, and overbite
were easily done. Visualization of marginal ridge heights, visualization of posterior
torque, and manipulation of the models were the most difficult. Conclusion:
Although all faculty reported that the majority of the ABO final model grading
system were easy to visualize, sixteen out of twenty reports that both types of
models are equally useful for assessing orthodontic treatment progression.
4

1
Co-senior author
2
Co-senior author
Chapter 1. Digital Models
1A. History
Three-dimensional digital models became available in orthodontics about
fifteen years ago. They are viewed, manipulated, and stored in personal
computers that use a few megabytes of storage. Various software allow digital
models to be used for many disciplines of dentistry that range from archiving,
treatment planning, treatment simulation, to prosthesis fabrication (Peluso et al.,
2004; Hajeer et al., 2004). In addition, additional hardware and devices, such as
CAD/CAM machines and 3D printers, have been developed in conjunction with
the advancement of digital models.
This move towards obtaining digital models, rather than plaster models,
has considerable advantages. Extensive storage facilities are no longer necessary,
models can be shared with colleagues or other specialists almost instantaneously,
and patients’ digital models are contained within their digital file for viewing at
any workstation (Asquith and McIntyre, 2012; Dalstra and Melsen, 2009).
However, more conservative clinicians who want to feel the physical models in
their hands or clinicians who do have little experience with computers may have
some difficulty in using these digital models.

5
1B. Digital Model Acquisition
A digital model of a patient’s teeth can be obtained by four different ways:
computed tomography, 3D laser scanning of a physical impression, 3D laser
scanning of a plaster model, or direct intra-oral scan.
Cone beam computed tomography (CBCT) is commonly used in dentistry
for treatment planning craniofacial syndromic cases, orthognathic surgical cases,
surgical dental impaction cases, and dental implant restoration cases. The
dentition can be extrapolated from a medium or large field CBCT with the
surrounding hard and soft structures removed from the view. However, the
current costs and the level of radiation exposure from these machines limit its
usefulness in daily clinical practice (Hajeer et al., 2004).
An indirect method of obtaining a digital model is through 3D laser
scanning. An alginate or polyvinyl siloxane (PVS) impression can be made while
the patient is in the office and either the impression or the poured up plaster
model can be placed in the scanner. Laser scanning has been demonstrated to be
accurate by capturing the impression or the model from multiple angles as it
rotates 360 degrees (Lu et al., 2000; Hirogaki et al., 2001; Kusnoto and Evans,
2002).

Unfortunately, even with the use of multiple angles, certain undercuts of
6
the impression or the model prove to be very difficult to capture (Hajeer et al.,
2004; Asquith and McIntyre, 2012).
Intraoral scanning systems have different technology. There are single
picture systems, such as Cerec’s Blue cam and Align Technology’s iTero, where a
single optical impression is taken when the camera is held still. Software then
stitches together the data it acquired and renders a 3D model (Kurbad, 20110).
There are also video systems that continuously acquire hard and soft tissues as
the camera moves along the arch. This technology allows direct capture of the
patient’s soft and hard tissue with no radiation exposure, and allows the capture
of difficult undercuts by directing the sensor towards different surfaces of
individual teeth.
Pretreatment of the tooth surface also varies from different scanning
systems. Scanners such as the Lava COS requires powdering of the tooth surface,
which allow proper light reflection and surface registration for the scanner. This
step may be time consuming and may result in errors due to irregular powdering
or saliva (Ender and Mehl, 2013). New intra-oral scanners, such as Cerec’s or Align
Tecnology’s no longer require any surface pretreatment, which simplifies the
process for the clinician.

7
1C. Uses in Dentistry
Dentists began using intra-oral digital scanners to obtain three-dimensional
models of soft and hard tissues for CAD/CAM systems. Single unit restorations,
fixed partial dentures, and implant planning are a few examples of early uses of
digital models and CAD/CAM technology (Ender and Mehl, 2013). Technology has
improved both the scan quality and the restoration fabrication quality since 3D
modeling and CAD/CAM was first introduced
A study done by Syrek (2010) compared fit of all-ceramic crowns made
from the Lava COS intraoral scanner system versus the conventional 2-step
impression technique. They found that the marginal discrepancies were clinically
acceptable in both groups, and that the occlusion obtained from both were equal.
However, the crowns fabricated from the Lava COS scan had better interproximal
contact point quality compared to the crowns made from conventional 2-step
impressions (Syrek et al., 2010).
The use of digital impressions for implants restorations, rather than
conventional impressions, have been reported to be more efficient in respect to
total treatment time (Lee and Gallucci, 2013). Conventional impressions required
longer preparation, longer working time, and longer retake time. Digital
impressions allowed rescans of segments, rather than an entire new scan. Lee, et
8
al. reported that conventional impressions would require more experience to
achieve the same level of proficiency than digital impressions (Lee and Gallucci,
2013).

The use of intra-oral scanners expanded into orthodontics once the
software was designed to stitch snapshots together into an entire arch, rather
than of a few teeth. Different software allow digital models to be used for
different objectives. Viewing software functions as study models that allow for
archiving, documentation, and treatment planning. Other software allow
manipulation of teeth or groups of teeth for custom treatment simulation, arch
wire fabrication, and clear aligners.

1D. Precision and Accuracy of 3D Models
Precision describes how close repeated measurements are to each other,
while accuracy describes how far the measurement deviates from the actual
dimensions of the measured object. The higher the precision, the more
predictable the measurement is. The higher the accuracy, the closer the results
are to the actual dimension. The accuracy of 3D impression and gypsum casts are
rare in the literature because knowing the real surface of the tooth or the dental
9
arch is rather difficult (Ender and Mehl, 2013; Ziegler, 2009).

The current gold
standard is the physical impression made with an elastomeric impression
material, resulting in a physical gypsum cast.
To measure the precision of the iTero intraoral scanner, Flugge (2013)
performed a study where the same mouth was scanned 10 different times. Each
scan was super imposed on each other for the best fit. The deviations were then
measured from the super impositions. The process was repeated with the iTero
scanner scanning a plaster model. The results showed that the average deviation
from 10 intraoral scans was 50 micrometers, while repeat scans of a plaster
model showed an average deviation of 25 micrometers. The higher precision of
extra-oral scanning could be due to patient movement, limited intra-oral space,
intra-oral humidity, and saliva flow. Deviations were high in the molar area, which
indicate that patient related factors had a strong influence.
In performing space analysis evaluations, digital models or plaster models
can be used. In a study where 25 alginate impressions were poured up into
plaster models, and then scanned into a digital model, mesial-distal tooth widths
were measured in both types of models. The space analysis was calculated and
the amount of crowding for both types of models was measured. It was found
that there was a slight (0.4 mm), but statistically significant difference found in
10
the maxillary models, but no significant difference in the mandibular models
(Leifert et al., 2009). The finding of a statistically significant but clinically
insignificant difference is consistent with other studies (Dalstra and Melsen, 2009;
Zilberman et al., 2003; Mullen et al., 2007).

Furthermore, the amount of time
taken to complete the space analysis was statistically significant, where the
analysis was completed 65 seconds faster with digital models (Mullen et al.,
2007).
When measuring tooth size, overbite, and overjet on plaster versus digital
models, Santoro, et al. studied 76 randomly selected pretreatment patients. A
statistically significant difference was found for tooth size and overbite, but these
differences were not clinically relevant. There was no difference found in the
measurement of overjet (Santoro et al., 2003).

11
Chapter 2. American Board of Orthodontics Final Model Grading Exam
2A. Final Model Grading System
In 1996, the American Board of Orthodontics (ABO) implemented an
objective grading system for their final certification exam. The ABO Model
Grading System contains eight criteria: alignment, marginal ridges, buccolingual
inclination, occlusal contacts, occlusal relationship, interproximal contacts, and
root angulation. Proper alignment is characterized by the alignment of the lingual
incisal edges of maxillary anterior teeth and labial incisal edges of mandibular
anterior teeth. In the posterior quadrants, the mesiobuccal and distobuccal cusps
should be in the same alignment in the mandible. For the maxilla, the central
grooves should all be in the same plane.
Marginal ridges for both maxillary and mandibular posterior teeth should
be on the same level or within 0.5 mm from each other. The canine premolar
contact and the mandibular 1
st
premolar are not graded. Buccolingual inclination
of posterior teeth shall be assessed by using a flat surface that is extended
between the occlusal surfaces of the right and left poster teeth. The straight edge
should contact the cusps and the buccal or lingual cusps should be within 1mm of
the straight edge.
12
The buccal cusps of the mandibular premolars and molars and the lingual
cusps of the maxillary premolars and molars should be contacting the occlusal
surfaces of opposing teeth. To measure occlusal relationship, the maxillary canine
cusp tip should align with the embrasure or contact between the mandibular
canine and adjacent premolar. The buccal cusps of the maxillary premolars should
align with the embrasures or contacts between the mandibular premolars and
first molar. The mesiobuccal cusps of the maxillary molars should align with the
buccal groves of the mandibular molars.
Overjet in the anterior region is characterized by the mandibular canines
and incisors contacting the lingual surfaces of the maxillary canines and incisors.
Interproximal contacts are assessed by viewing the models from an occlusal
perspective. The mesial and distal surfaces of the teeth should be in contact with
each other. Root angulation is assessed through a panoramic radiograph and the
roots should be parallel to one another and oriented perpendicular to the occlusal
plane.

2B. Common errors in preparing for and completing the ABO clinical exam
The Cast-Radiograph Evaluation is a measure of the results of treatment
based on the analysis of the final dental casts and dental radiographs. The most
13
common deficiencies found are alignment, buccolingual inclination inadequacies,
marginal ridge discrepancies, and root angulation problems. Lateral incisors and
second molars most often lack adequate alignment (English et al., 2011).

2C. Digital Models for the Objective Grading System
Using digital models to submit for the American Board of Orthodontics Final
Model Exam has not yet been approved. There are currently two preliminary
studies that evaluated the accuracy of scoring digital models with OrthoCAD’s
ABO objective grading system software. A study by Costalos (2005) evaluated 48
models for 24 patients and found that similar scores were found for both models
in marginal ridges, occlusal contacts, occlusal relationships, overjet, and
interproximal contacts. Scores for alignment and buccolingual inclination were
found to be significantly different. Another study by Hildebrand, et al. evaluated
36 cases and found that the total scores were significantly different between
plaster and digital models, which differed by 9 points on average. The differences
were due to alignment, occlusal contact, and overjet (Hildebrand et al., 2008).
Future advancements in software will be necessary for improved accuracy for
digital scoring for the ABO.
14
Chapter 3. Our Current Study
3A. General Overview
In evaluating the progress of orthodontic treatment for ABO qualified
cases, it is common for orthodontic residents to take impressions for progress
models. This allows the resident and the supervising faculty to assess what
modifications are needed according to the grading criteria stated above. The
downside of this process is that due to the setting time of the plaster, the patient
is often sent home before any model evaluation can be done.
Using the Align Technology iTero intra-oral scanner will allow the digital
impression and the model ready to be viewed while the patient is still present.
Therefore, any adjustments to treatment can be made at the same day that the
model was analyzed. The objective of this study was to determine if digital models
are as useful as plaster models in assessing treatment progress per ABO’s
standards.

3B. Align Technology iTero Intraoral Scanner
Align Technology, Inc. has provided the Orthodontic Department at the
University of Southern California School of Dentistry a current model iTero
intraoral scanner for use in this study. The iTero system uses a laser scanning
15
protocol known as “parallel confocal,” that allows the scanner to measure the
distance from the scanner’s sensor tip to the object (Garg, 2008; van der Meer et
al., 2012; Henkel, 2007). Single 3D frames are captured on each scan and are
stitched with other frames to compile a complete 3D model (Figure 1). The
clinician takes several scans throughout both arches that result in a model with
over 100,000 data points (Garg, 2008).
The iTero was tested on 1,600 cases in multiple offices over a 24

month
period, and was introduced nationally in 2007. Double blind studies revealed that
patients were able to recognize a difference in time for impressions with the iTero
versus the conventional PVS impression. Patients also reported overall
satisfaction with the reduction of gagging, anxiety, poking, stretching, and post
impression discomfort (Garg, 2008).

16

Figure 1. Components of the iTero parallel confocal scanner. A laser beam (red)
is projected onto an object. The reflected beam (purple) is led through a focal
filter where only the image that lies in its focal point is allowed to pass through
into the sensor.
17
Chapter 4. Hypotheses
We hypothesize that digital impressions made with the iTero intra-oral
scanner allows better evaluation of treatment progress based on the final model
grading system set by the American Board of Orthodontics.
18
Chapter 5. Materials and Methods
Twenty patients from the University of Southern California’s Advance
Orthodontic Program were randomly selected to participate in the study. The
inclusion criteria included: (1) Full size stainless steel or beta-titanium wire (equal
to or greater than 0.016 x 0.022 for 0.018 bracket slots, equal to or greater than
0.019 x 0.025 for 0.022 bracket slots), (2) patients required comprehensive
orthodontic treatment, and (3) treatment was at the detail and finishing stages of
orthodontic treatment. The exclusion criteria was: (1) Surgical orthodontic
treatment, (2) two phase orthodontic treatment, (3) transfer patients from
outside orthodontists or orthodontic programs, (4) interdisciplinary patients, and
(5) craniofacial dysmorphology patients.
Each patient was scanned with the iTero Intraoral Scanner using the
iRecords option. The maxillary arch, mandibular arch, and occlusion were scanned
with the appliance still in the mouth. Once the scan was completed and the digital
model was constructed and viewed with scanner’s native software. Instructions to
manipulate the model were given to the ABO certified faculty who was
supervising the case. The faculty was allowed to evaluate the models once they
demonstrated the ability to rotate, pan, zoom, isolate an arch, show grid, and use
the ruler tool.
19
A survey instrument of eleven questions was developed to query the
clinical instructor to determine if the real time intra-oral scan is the same, better,
or worse in evaluating overall treatment progress (Figure 2). One of the eleven
questions with a single three choice question served as the primary outcome
variable (ordinal variable), with the remaining ten questions as secondary
outcomes of the survey. Additional comments were optional at the end of the
survey.
This study was submitted to and approved by the University of Southern
California Health Sciences Campus Institutional Review Board.

20

Figure 2. Survey for Model Evaluation. Each faculty was given this survey to fill
out while the patient was still present, chair-side.

21
Chapter 6. Results
Twenty surveys were collected from ten faculty instructors who evaluated
treatment progress of patients that they were supervising. Results are shown in
figure 3.

Figure 3. Survey Results. Evaluator agreement on usefulness and visibility of the
10 components asked in the survey.

All twenty faculty instructors strongly agree (13 of 20) or agree (7 of 20)
that the digital models were a useful tool in assessing treatment progress. All
twenty also either strongly agree, agree, or neutrally thought that tooth
22
alignment, overbite, overjet, occlusal contacts were clearly visible. Overbite was
the easiest to evaluate (20 SA), followed by overjet (18 SA, 2 A), tooth alignment
(16 SA, 4 A), and occlusal contacts (8 SA, 11 A, 1 N) as shown in figures 4-7.
Fifteen instructors strongly agreed and five agreed that this tool is beneficial in
improving treatment and would incorporate it into their private practice.

Figure 4. Frontal View. Visibility of overbite of anterior teeth can be seen through
the frontal view of the model.

23

Figure 5. Overjet. Moving the model for an underside view to evaluate anterior
overjet.

24

Figure 6. Alignment. Removing an arch and orienting the model to an occlusal
view to evaluate tooth alignment (rotations).

25

Figure 7. Occlusal Contacts. With both arches in occlusion, occlusal contacts of
maxillary palatal cusps can be seen in occlusion with manidbular marginal ridges
and central fossas.

Manipulation of the models were the most difficult with five disagreeing
that manipulation was as convenient as handling plaster models. Torque of the
molars and marginal ridge heights were the next most difficult with two
disagreeing for each that they are clearly visible (Figure 7).

26

Figure 8. Posterior Torque. Removing one arch and orienting the model for a
postierior view allows visibility of posterior torque (bucco-lingual inclination).

The result of the overall preference for the type of progress model is shown
in figure 9. Fifteen out of the twenty survey results showed a preference for both
types of models. Two preferred digital over plaster, while three preferred plaster
over digital.
27

Figure 9. Preference of Model Type. Survey results for which impression method
the evaluator would prefer to use.

28
Chapter 7. Discussion
With Intra-oral scanners getting faster and more accurate, they becoming
more common as a replacement for alginate impressions and plaster models.
Digital models eliminate the need for large amounts of physical storage space to
keep patient records. The real time scan also allows the doctor to evaluate the
models and make the proper treatment adjustments at the same day. Full mouth
scans and the digital construction of the models can be ready for analyzing in
under 10 minutes, which is an advantage over plaster models. With plaster
models, the patient is usually dismissed from the office before the models are
ready. Therefore, any modifications need based on the plaster model will not be
done until the patient’s next visit.
One of the new concepts of using a three dimensional model versus a
physical plaster model is using the mouse to manipulate the model. Using the
mouse to rotate, pan, and zoom may be difficult to those who are not tech savvy.
This aspect of digital models was the most difficult for the faculty. However,
faculty who often use 3D models in their office, such as CBCT scans or Invisalign’s
Clincheck, tend to have an easier time moving and rotating the models as they
desired.
29
Once the user became accustomed to manipulating the models, overall
reports of visualization and usefulness were positive. With the ability to zoom in
and the clarity of the models, a majority of the ABO’s grading criteria can be easily
evaluated. Marginal ridge heights and torque of posterior teeth were the difficult
to visualize. This may be due to the fact that the iTero software is primarily for
digital impression taken, and not for model evaluation. Once additional features,
such as slicing of the models or contrast adjustments, are added into the
software, its usability will improve.
Almost all faculty reported that they would be comfortable in using either
plaster models or digital models for progress model evaluation. The advantages
and disadvantages of both plaster and digital models are listed in Table 1. Difficult
views from a visual clinical exam can easily be seen on the model, and the model
can be zoomed in for more detail. Any adjustments for the patient’s treatment
after reviewing the model can also be done in the same visit. Traditionally, with
plaster models, the modifications would be done on the next visit because the
patient would be dismissed prior to complete setting of the plaster. However,
now the patient can come into the office, be scanned by a team member, and
have the digital model ready for the exam by the time the doctor comes to see
the patient.
30

Advantages Disadvantages
Digital
Model acquisition time Cost
Model visibility Dry sensation for patients
Patient still present Steep learning curve
Comfort Difficult movement/manipulation
Can add scans on deficient areas Cannot orient arches in different occlusion
Storage
Clean
Plaster
Physical "feel" of models Storage
Can orient models in any occlusion Discomfort with alginate (taste & gagging)
Can be used for model surgery Need to redo entire impression if deficient
Model setting time
Table 1. Plaster versus Digital. Summary of the advantages and disadvantages
between the two types of models.

Patient education is also another benefit of having the digital model ready
while the patient is still present. Patients can see how their treatment is
progressing, and comparisons of initial or previous digital models can be loaded
on to the screen almost immediately. They can also visualize what the goals are
for the different procedures in orthodontic treatment, such as what rubber bands
will do, and what to expect by next visit with good cooperation.
The group of faculty that participated in this study has a range of
experience regarding clinic and technology. An improvement to this study would
have been more training for them so that they would be more comfortable in the
user interface of the software. It would be interesting to see in a future study if
31
the results would change if they were more comfortable in moving the models to
the desired views. Manipulating the model to see marginal ridges, for example,
can be challenging when the model is in three dimensions, but the mouse control
for rotation is only in two dimensions. Furthermore, adding the demographics of
the faculty to the study would have shown how age and computer experience
would have influenced the results. Determining whether there is a difference
between the younger and older faculty, and whether both groups would be
comfortable in switching to complete digital records would be very useful in a
follow up study.

32
Chapter 8. Conclusions
This study evaluated the use of digital orthodontic progress models, in place of
conventional plaster models, to determine treatment progress. While most
components measured by the American Board of Orthodontic’s Objective Grading
System was visible, marginal ridge heights and posterior torque were more
difficult to visualize. With further advancement in software development,
improved visibility and usability of 3D models may replace conventional plaster
models in the near future.

This study was approved by the IRB. ID: HS-14-00455
33
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36
Figures and Tables
Figure 1. Components of the iTero Parallel Confocal Scanner 16
Figure 2. Survey for Model Evaluation 20
Figure 3. Survey Results 21
Figure 4. Frontal View 22
Figure 5. Overjet 23
Figure 6. Alignment 24
Figure 7. Occlusal Contacts 25
Figure 8. Posterior Torque 26
Figure 9. Preference of Progress Model Type 27
Table 1. Plaster versus Digital 30

Abstract (if available)

Abstract Objective: Progress models are commonly made during the detailing and finishing stages of orthodontic treatment with alginate impressions and plaster. Three-dimensional intraoral scanners, such as Align Technology Inc.’s iTero, can be used in place of traditional models. The objective of this study was to assess whether the three-dimensional models were useful in visualizing treatment progress per the American Board of Orthodontics (ABO) final model grading system. Methods: In this prospective study, 20 patients in the detailing and finishing stages of orthodontic treatment were scanned using the iTero intraoral scanner. 10 ABO certified faculty orthodontists of the University of Southern California used the three-dimensional model to assess treatment progress and completed a survey to determine which sections of the final model grading system were easy or difficult to visualize. Results: Assessing treatment progress and visualizing tooth alignment (rotation), occlusal contacts, overjet, and overbite were easily done. Visualization of marginal ridge heights, visualization of posterior torque, and manipulation of the models were the most difficult. Conclusion: Although all faculty reported that the majority of the ABO final model grading system were easy to visualize, sixteen out of twenty reports that both types of models are equally useful for assessing orthodontic treatment progression.

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University of Southern California Dissertations and Theses

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Asset Metadata

Creator Budiman, Eric (author)

Core Title Use of digital models to assess orthodontic treatment progress

School School of Dentistry

Degree Master of Science

Degree Program Craniofacial Biology

Publication Date 04/22/2015

Defense Date 03/06/2015

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag 3D scanner,digital model,digital scanner,iTero,OAI-PMH Harvest,orthodontic treatment,Progress

Format application/pdf (imt)

Language English

Contributor Electronically uploaded by the author (provenance)

Advisor Sameshima, Glenn T. (committee chair), Grauer, Dan (committee member), Paine, Michael L. (committee member)

Creator Email budiman.eric@gmail.com,ebudiman@usc.edu

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c3-556536

Unique identifier UC11300495

Identifier etd-BudimanEri-3364.pdf (filename),usctheses-c3-556536 (legacy record id)

Legacy Identifier etd-BudimanEri-3364.pdf

Dmrecord 556536

Document Type Thesis

Format application/pdf (imt)

Rights Budiman, Eric

Type texts

Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

Access Conditions The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the a...

Repository Name University of Southern California Digital Library

Repository Location USC Digital Library, University of Southern California, University Park Campus MC 2810, 3434 South Grand Avenue, 2nd Floor, Los Angeles, California 90089-2810, USA