the cutting edge

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This column is now compiled by JCO Technology Editor Marc S. Lemchen, DMD. To help keep our readers on The Cutting Edge, Dr. Lemchen will spotlight a ...

©2016 JCO, Inc. May not be distributed without permission. www.jco-online.com

THE CUTTING EDGE This column is now compiled by JCO Technology Editor Marc S. Lemchen, DMD. To help keep our readers on The Cutting Edge, Dr. Lemchen will spotlight a particular area of orthodontic technology every few months. Your suggestions for future subjects or authors are welcome.

In this month’s Cutting Edge article, the authors evaluate the use of digital study models in daily orthodontic practice. They sent 31 questions to a random selection of 2,300 orthodontists, using SurveyMonkey.com; about 9% responded. As with other research of this type, the data could be heavily influenced by the authors’ choice of collection method. Online surveying creates an environment in which individuals more comfortable with computers are more likely to complete the questionnaire. The respondents would also be more likely to use intraoral scanners, cone-beam computed tomography (CBCT), and digital study models.

That said, I found the information to be fascinating. Various methods used to capture the data needed for digital study models are explored, and the results of the survey are reported in selfexplanatory graphs and flow charts. I encourage you to spend some time with this article, looking for the underlying trends as much as the raw numbers. W. RONALD REDMOND, DDS, MS

Trends in the Use of Digital Study Models and Other Technologies Among Practicing Orthodontists JAE HYUN PARK, DMD, MSD, MS, PhD JONNA LASLOVICH, DMD

T

Dr. Park

Dr. Laslovich

Dr. Park is a Professor and Chair, Postgraduate Orthodontic Program, and Dr. Laslovich is a former postgraduate orthodontic resident, Arizona School of Dentistry and Oral Health, A.T. Still University, 5835 E. Still Circle, Mesa, AZ 85206. Dr. Park is also an Adjunct Professor, Graduate School of Dentistry, Kyung Hee University, Seoul, Korea. E-mail Dr. Park at [email protected]

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he practice of orthodontics is rapidly changing to adapt to our digital world. Recent developments in three-dimensional digital models, digital intraoral scanners, and CBCT are at the forefront of these technological advances. Orthodontic study models have long been the foundation for proper diagnosis, treatment planning, and case evaluation. Because storage space is a common constraint, however, more and more

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be accompanied by either plaster models or 3Dprinted stereolithic models. A study by Shastry and Park revealed that more than one-third of the accredited postgraduate orthodontic programs in the United States and Canada are already using digital

orthodontists are switching to digital records. Several studies have verified the accuracy and validity of digital study models.1-3 The ABO accepts pretreatment, progress, and final digital models for clinical exams, although final digital models must

A. Advantages of plaster models

B. Disadvantages of plaster models

3D feel

Storage and retrieval

Cost Simplicity of fabrication

Potential for damage

Can be mounted ABO requirements 0%

25%

50%

75%

Difficulty in information sharing (electronically)

100%

0%

Advantages

25% 50% 75% 100%

Disadvantages

E. When do you plan to switch to digital models?

C. Reasons for not switching to digital models Cost

Plaster Models

1 year or less

Loss of 3D feel

2-5 years

Differences between models and occlusion

More than 5 years

When?

No plans at this time

Concerns

Yes (34%) 0%

25%

50%

No (29%)

Switch to digital?

75% 100%

Technical requirements Lack of universal software for sharing 0%

25%

50%

75% 100%

Undecided (37%) D. Does your practice plan to switch to digital models in the future?

Undecided Yes No 0%

25%

50%

75%

100%

Fig. 1  Responses from users of predominantly plaster models.

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online questionnaire using SurveyMonkey.com was submitted to the AAO Survey Review Committee of the AAO Board of Trustees. On approval, the AAO’s Partners in Research Program distributed the anonymous, voluntary questionnaire to 2,300 randomly selected AAO members. In an attempt to improve the response rate, a follow-up reminder e-mail was sent one month after the initial e-mail. The survey consisted of 31 questions, divided between digital and plaster models in a logical sequence. (The full survey can be viewed through a link in this article at www.jco-online. com.) Each question was presented in a multiplechoice format with the option to enter additional comments. Data were analyzed using Excel.

study models for the majority of cases treated in their programs.4 Noble and colleagues found that more than 90% of orthodontic residents plan to use digital imaging programs when they enter practice.5 Digital scanners and CBCT go hand-in-hand with digital models. Intraoral scanners can render accurate images and, as a result, have allowed orthodontic offices to eliminate the need for both impression material and plaster.6 Taking it one step further, software has been developed to perform model analyses directly from CBCT images, potentially eliminating the need for scanners as well.7,8 The purpose of this study was to investigate the use of digital study models, intraoral scanners, and CBCT among practicing orthodontists, providing an up-to-date picture of technology trends in everyday practice.

Results

Materials and Methods

Overall, 213 responses were collected, for a 9.3% response rate. The majority of respondents (81%) indicated that they owned private prac-

The A.T. Still University Institutional Review Board granted approval for this study. An

Another Orthodontist

Residency Program

Company Representative or Orthodontic Supplier

Continuing-Education or Professional Meeting

0

5

10

15

20

25

30

35

40

45

50

Percentage

Fig. 2  Reported methods of predominantly plaster-model users’ introduction to digital models.

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tices, with a range of one to 36 years in practice (mean = 17.3). Of the responding clinicians, 54% used predominantly plaster study models in their practices, while 46% used predominantly digital models. Figure 1 is a flow diagram illustrating the responses from predominantly plaster-model users.

Three-dimensional feel, cost, and simplicity of model production were the main reasons cited for preferring plaster models. Almost all of the users (98%) indicated that storage and retrieval were the biggest disadvantages, followed by the potential for damage (65%) and difficulty in electronic information sharing (47%). Fully 72% of the plaster-

B. Which of the following digital models is your practice predominantly using?

A. How long have you used digital models? More than 10 years

OrthoCAD

6-10 years

Type

1-5 years

SureSmile Ortho Insight 3D DigiModel

Less than 1 year

emodel 0%

25%

50%

75%

O3DM

100%

0%

25%

50%

75%

100%

How long?

Advantages

F. How does the overall cost of digital models compare to plaster models in your practice?

C. What are the reasons to switch to digital models? Easy storage and retrieval

No difference

Digital Models

Increased overall cost

New technology Avoid damage/loss Reduce measurement times

Reduced overall cost

ABO accepting initial digital models 0%

25%

50%

75%

0% 25% 50% 75% 100%

100%

Cost

Future use?

E. Why do you not plan to use digital study models for the majority of your cases?

D. Does your practice plan to continue using digital models?

Cost Technical issues

Yes

If not, why?

Difference between models and occlusion Lack of universal software sharing

No Unsure

Two-dimensional feel 0%

25%

50%

75%

100%

0%

25%

50%

75%

100%

Fig. 3  Responses from users of predominantly digital models.

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Figure 3 depicts the responses from predominantly digital-model users. These orthodontists reported being introduced to digital study models in a residency program (39%), by a company representative or orthodontic supplier (25%), at a continuing-education or professional meeting (25%), or by another orthodontist (11%), as shown in Figure 4. The majority had used digital models for one to five years (57%) or six to 10 years (27%). By far the most popular virtual-model program was OrthoCAD* (76%). Nearly 96% indicated that ease of storage and retrieval was the primary reason for switching to digital models, followed by new technology, avoiding damage to or loss of plaster models, reducing measurement time, and ABO acceptance of initial (pretreatment) digital models. When asked if their companies had converted their proprietary digital file formats to a universal format accepted by the ABO, 43% of the

model users reported being familiar with digital model programs by way of a continuing-education or professional meeting (38%), company representative or orthodontic supplier (32%), residency program (25%), or another orthodontist (6%), as shown in Figure 2. When asked if they planned to switch to digital study models in the future, 34% said yes, 29% said no, and 37% were undecided. The major reasons given for not switching to digital models were the cost and loss of 3D feel; less common concerns were inconsistency between mounted models and correct bite, technical requirements, and lack of universal software for electronic sharing. Almost 62% of the plastermodel users who planned to switch said they would do so within five years, while 7% planned to wait more than five years (the remainder were undecided). About 20% of the users said they would be influenced to switch from plaster to digital models if the ABO started accepting final (post-treatment) digital models without accompanying physical models.

*Registered trademark of Align Technology, San Jose, CA; www. aligntech.com.

Another Orthodontist

Continuing-Education or Professional Meeting

Company Representative or Orthodontic Supplier

Residency Program

0

5

10

15

20

25

30

35

40

45

50

Percentage

Fig. 4  Reported methods of predominantly digital-model users’ introduction to digital models.

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users said yes, 2% said no, and 55% were unsure. Among the digital-model users, 56% reported also using intraoral scanners, with iTero* being the most popular (86%). Scanners were most commonly used for their compatibility with digital orthodontic systems such as Invisalign,* Insignia,** Harmony,*** or SureSmile†; for study models; and to fabricate appliances and retainers. Only 14% of the digital-model users reported also using CBCT to obtain orthodontic records. Seventythree percent of the CBCT users indicated that they would consider using CBCT in place of plaster models or digital models, but almost 75% of the respondents who did not use CBCT were unsure why they chose not to use CBCT in place of plaster or digital models. When asked what type of orthodontic record was used to make their digital study models, the majority said they used an intraoral scan (53%), followed by conventional impressions (39%), CBCT (5%), and both conventional impressions and intraoral scans (3%). More than 54% of the digital-model users reported a reduction in overall cost compared to conventional models, 27% reported an increase in cost, and 19% reported no difference. More than 84% of these clinicians planned to continue using digital study models for the majority of their cases. Cost, technical issues and support, and inconsistency between mounted models and correct occlusion were the most common reasons why 10% of the digital-model users did not plan to continue using such models for most of their cases. Discussion Digital study models can be stored virtually rather than physically, thus reducing the need for storage space and associated costs. Moreover, digital models can be viewed at multiple locations or *Registered trademark of Align Technology, San Jose, CA; www. aligntech.com. **Ormco Corporation, Orange, CA; www.ormco.com. ***American Orthodontics, Sheboygan, WI; www.americanortho. com. †Registered trademark of OraMetrix, Inc., Richardson, TX; www. suresmile.com.

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from any office linked to the practice’s central server, and the models can be transferred electronically to insurance companies, colleagues, and other specialists.9,10 Almost half of the practicing orthodontists we surveyed used predominantly digital study models—a proportion that will likely continue to increase as current and future residents transition into practice.5 It is also important to note that 34% of the plaster-model users in our survey planned to switch to digital study models, most within the next five years. Intraoral scanners are also gaining acceptance in orthodontic practice. The iTero was the most popular scanner among our respondents, probably due to its compatibility with the Invisalign system. Recent research has shown that the iTero’s linear and crowding measurements are interchangeable with manual measurements, making it an acceptable substitute for a traditional impression in creating digital models for diagnostic purposes.6,11 Although Grünheid and colleagues also verified the accuracy of digital models made from intraoral scans, they found that most patients actually preferred traditional impressions because they required less time in the chair.12 Our relatively high percentage of respondents using conventional impressions to make digital models may be a reflection of patient preference, or simply an indication of a transition period from traditional techniques to full adoption of the new technology. While most respondents reported using intraoral scanners for study models or in conjunction with digital orthodontic systems, many also indicated that intraoral scanners were being used for appliance fabrication or 3D-printed models—a rapidly growing trend.13,14 Recent advances in technology have also made it possible to render digital models from CBCT scans, which can be viewed, manipulated, and evaluated with dedicated software. All the anatomical structures captured by CBCT (dental roots, TMJ, bone levels, positions of impacted teeth) can be viewed in conjunction with the structures of a traditional model. Disadvantages of this technology include an inability to display gingival tissue and concerns regarding unnecessary exposure to radiation.15

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Studies have shown that digital models obtained from CBCT provide accurate diagnostic information, including linear measurements for overjet, overbite, and crowding.16,17 Therefore, it is not unreasonable to assume that an orthodontist will soon be able to collect all diagnostic records (except intraoral and extraoral photographs) from a single scan. The potential for increased efficiency, reduced cost and radiation exposure due to technological improvements, and compatibility with digital orthodontic systems will likely result in an increase in the percentage of clinicians using CBCT in their offices. Finally, respondents to our survey were asked several questions regarding the use of digital study models for the ABO certification exam. If the ABO were to start accepting final (posttreatment) digital models, more than 80% of the plaster-model users said they would be no more likely to switch to digital models. Moreover, 55% of the digital-model users were unsure whether their companies could even convert their proprietary digital file formats to a universal format acceptable to the ABO. Of the orthodontists surveyed, 43% were already ABO-certified and, therefore, might not have been concerned about the certification process. They did not, however, consider recertification examination. Still, the acceptance of final digital models for the ABO clinical exam is an issue that should not be overlooked, since the majority of residents and new practicing orthodontists—the most likely candidates for board certification—plan to use digital models in their orthodontic practices.5 It is important to note the limitations of this study, including the response rate and possible selection bias. The inclusion of “digital models” and “technology” in the survey title may have influenced the decision of prospective participants to answer the questionnaire. The online survey method may also be biased toward practitioners who are more computer-literate and therefore more likely to use technology in their offices. ACKNOWLEDGMENT: We thank Dr. James D. Seward for assistance with the statistical analyses.

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REFERENCES 1.  Quimby, M.L.; Vig, K.W.; Rashid, R.G.; and Firestone, A.R.: The accuracy and reliability of measurements made on computer based digital models, Angle Orthod. 74:298-303, 2004. 2.  Costalos, P.A.; Sarraf, K.; Cangialosi, T.J.; and Efstratiadis, S.: Evaluation of the accuracy of digital model analysis for the American Board of Orthodontics objective grading system for dental casts, Am. J. Orthod. 128:624-629, 2005. 3.  Fleming, P.S.; Marinho, V.; and Johal, A.: Orthodontic measurements on digital study models compared to plaster models: A systematic review, Orthod. Craniofac. Res. 14:1-16, 2011. 4. Shastry, S. and Park, J.H.: Evaluation of the use of digital study models in postgraduate orthodontic programs in the United States and Canada, Angle Orthod. 84:62-67, 2014. 5. Noble, J.; Hechter, F.J.; Karaiskos, N.E.; Lekic, N.; and Wiltshire, W.A.: Future practice plans of orthodontic residents in the United States, Am. J. Orthod. 135:357-360, 2009. 6.  Akyalcin, S.; Cozad, B.E.; English, J.D.; Colville, C.D.; and Laman, S.: Diagnostic accuracy of impression-free digital models, Am. J. Orthod. 144:916-922, 2013. 7.  De Waard, O.; Rangel, F.A.; Fudalej, P.S.; Bronkhorst, E.M.; Kuijpers-Jagtman, A.M.; and Breuning, K.H.: Reproducibility and accuracy of linear measurements on dental models derived from cone-beam computed tomography compared with digital dental casts, Am. J. Orthod. 146:328-336, 2014. 8.  Kau, C.H.; Littlefield, J.; Rainy, N.; Nguyen, J.T.; and Creed, B.: Evaluation of CBCT digital and traditional models using the Little’s Index, Angle Orthod. 80:435-439, 2010. 9. Joffe, L.: OrthoCAD: Digital models for a digital era, J. Orthod. 31:344-347, 2004. 10.  Peluso, M.; Josell, S.; Levine, S.; and Lorei, B.: Digital models: An introduction, Semin. Orthod. 10:226-238, 2004. 11. Flügge, T.V.; Schlager, S.; Nelson, K.; Nahles, S.; and Metzger, M.C.: Precision of intraoral digital dental impressions with iTero and extraoral digitization with the iTero and a model scanner, Am. J. Orthod. 144:471-478, 2013. 12.  Grünheid, T.; McCarthy, S.D.; and Larson, B.E.: Clinical use of a direct chairside oral scanner: An assessment of accuracy, time, and patient acceptance, Am. J. Orthod. 146:673-682, 2014. 13. Groth, C.; Kravitz, N.D.; Jones, P.E.; Graham, J.W.; and Redmond, W.R.: Three-dimensional printing technology, J. Clin. Orthod. 48:475-485, 2014. 14.  Hazeveld, A.; Huddleston Slater, J.J.; and Ren, Y.: Accuracy and reproducibility of dental replica models reconstructed by different rapid prototyping techniques, Am. J. Orthod. 145:108-115, 2014. 15. Lightheart, K.G.; English, J.D.; Kau, C.H.; Akyalcin, S.; Bussa, H.I. Jr.; McGrory, K.R.; and McGrory, K.J.: Surface analysis of study models generated from OrthoCAD and cone-beam computed tomography imaging, Am. J. Orthod. 141:686-693, 2012. 16. Kau, C.H.; Richmond, S.; Palomo, J.M.; and Hans, M.G.: Three-dimensional cone beam computerized tomography in orthodontics, J. Orthod. 32:282-293, 2005. 17.  Baumgaertel, S.; Palomo, J.M.; Palomo, L.; and Hans, M.G.: Reliability and accuracy of cone-beam computed tomography dental measurements, Am. J. Orthod. 136:19-28, 2009.

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