The value of orthodontic study models for diagnosis and treatment planning: a survey

Drs. Nathan Yetter and Donald J. Rinchuse investigate whether orthodontic e-models and/or plaster models are useful

Introduction: The purpose of this survey study was to investigate whether orthodontic e-models and/or plaster models are perceived to be useful for orthodontic diagnosis and treatment planning.
Methods: An email invitation from the American Association of Orthodontists, AAO Partners in Education, was sent to a random selection of 2,300 members of the AAO in the United States requesting participation in a 13 question online survey (SurveyMonkey®).


Results: Of the 2,300 orthodontists randomly surveyed, 260 completed the survey for a response rate of 11.30%. 67.69% reported always taking pretreatment study models while only 33.08% take posttreatment models. Better diagnostics was cited by 66.54% of respondents as the reason for taking pretreatment models. At the same time, 57.31% also reported legal reasons as a motivation for taking pretreatment models. 27.31% said they never look at the pretreatment models after treatment has begun. While 29.23% strongly agree that having pretreatment study models is important to making treatment decisions, 25.77% strongly disagreed. 71.54% of survey respondents reported practicing orthodontics for more than 10 years with the majority of those practicing for more than 20 years.

Nathan YetterConclusions: This study demonstrated the wide range of opinions on taking pretreatment study models and the reasons for taking them. There seemed to be a trend among younger orthodontists toward not taking pretreatment study models as the quality of digital photography increases and more emphasis is placed on having quality photographic images.


The success of orthodontic treatment is highly correlated with a correct diagnosis and proper execution of a thorough treatment plan.1 An experienced clinician often knows what the diagnosis and treatment plan for most patients will be at the initial examination. In fact, Mr. Bud Schulman2 has been advocating case acceptance at the first visit for many years. He stated, “I believe in some cases, possibly 80% of the cases, they can tell immediately that orthodontics is called for and what the approach may be… I believe the tendency throughout the profession is to reduce the entry-visit procedure.”

Historically, orthodontists have used a thorough medical history, photographs, plaster models, cephalometric radiographs, and panoramic radiographs in conjunction with a comprehensive clinical examination to make a diagnosis. There have been many studies that have confirmed the usefulness and validity of the records orthodontists traditionally use for diagnosis and treatment planning.5,6,7,8,9,14 Currently, the American Association of Orthodontics4 recommends that complete orthodontic records should include the following: pretreatment and posttreatment intraoral and extraoral photographs, models (either plaster or digital), panoramic radiographs, lateral cephalometric radiograph with a diagnostic tracing, as well as any other records deemed necessary for the individual patient.

With the ever-evolving technological advancements, adaptations to the necessary records have and will continue to change. Orthodontists may be required in the near future to convert all their records to the digital form. In line with these changes, e-models have been accepted as an adequate substitute for plaster models and have subsequently made it easier for orthodontic offices to become digital. Stevens, et al.,5 evaluated the validity, reliability, and reproducibility of plaster versus digital study models and found that digital models would not cause an orthodontist to make a different diagnosis compared with plaster models.

As the quality of digital photography has become better and used in most (if not all) orthodontic offices, digital pretreatment photographs have evolved into a critical pretreatment record. Digital photos are available immediately at the initial patient visit and can be retaken when needed. When properly captured, they offer a complete view of the patient’s dental malocclusion, soft tissue esthetics, and some skeletal orientation. It can be argued that more clinical information can be derived from pretreatment photographs than from plaster or digital patient models. Also, digital models are typically not available for at least 5 to 7 days after the initial patient visit, and usually a diagnosis and treatment plan are already formulated. Plus, as already stated, many clinicians advocate a one-visit case acceptance approach which would eliminate the use of plaster models for diagnosis and treatment planning.

Arguably, the most important piece of information that contributes to a proper diagnosis is the initial clinical examination. This is the time when the evaluating doctor will usually formulate a diagnosis and treatment plan based on what he or she sees clinically. Panoramic and cephalometric radiographs can be available during this exam (plaster or digital) as well as digital photographs. The models are typically not available during the initial evaluation. This raises the question as to what contribution study models have in reference to diagnosis and treatment planning and if having pretreatment study models has any effect on the treatment outcome.

Materials and methods

A random sample of 2,300 orthodontists who were active members of the AAO were sent an email invitation to participate in this 13-question survey. The email invitation to participate in the survey included a description of the survey topic and its relevance and importance to the field of orthodontics. It encouraged all to participate. The first email invitation was sent on August 27, 2013, in which 159 responses were collected. A secondary reminder was sent on September 11, 2013, which generated another 101 responses. The survey was closed on October 7, 2013. Data collection and analysis were obtained through SurveyMonkey, and descriptive statistics were used.


The survey was sent to 2,300 orthodontists who were active members of the AAO. Of the 2,300 orthodontists, 260 completed the survey, for a response rate of 11.30%. The Table shows the demographic information of the survey respondents (Nos. 9-12) as well as a summary of the results (Nos. 1-8).

It was reported that 67.69% of those who responded always took pretreatment study models. 66.54% said they take pretreatment study models (plaster or digital) for better diagnostics while 57.31% also reported taking them for legal reasons. In response to whether having study models was important to making treatment decisions, 25.77% strongly disagreed that having pretreatment study models is important to making treatment decisions while 29.23% strongly agreed. Overall, there were wide-ranging views on whether it is important to have pretreatment study models.


Pretreatment orthodontic study models have been used for many years in diagnosis and treatment planning for orthodontic patients. They have historically been used as a diagnostic tool and as a legal record of the patients’ condition before the start of treatment. Information can be gathered from dental models that include overbite, overjet, tooth sizes, arch lengths, and transverse distances.13 There has been discussion and debate over the diagnostic value of pretreatment study models for a long time. Many doctors are taking pretreatment study models only because they feel that they must in order to protect themselves legally. The results of this survey indicate that a majority of orthodontist (67.69%) are taking pretreatment study models. The results also demonstrate that many orthodontists (23.08%) are not taking them for the majority of cases. Many orthodontists (57.31%) also cited legal reasons as a motivating factor for taking pretreatment study models.

As orthodontics continues to evolve, evidence-based practice is a primary focus that should be strived for. As stated in the textbook Evidence-Based Clinical Orthodontics, “The orthodontist’s focus for clinical decision making should be on treatment protocols and strategies that are proven to be both efficacious and safe.”14 The question that should be asked is, What scientific evidence exists that supports the value of pretreatment study models for making better diagnostic and treatment planning decisions? In this survey 38.08% of those who responded either strongly or somewhat disagreed that having study models is important to making treatment decisions. Callahan, et al.,13 studied the value of plaster models in orthodontic diagnosis and treatment planning. They presented pretreatment records that included intraoral and extraoral photos, panoramic, and traced lateral cephalometric radiographs to four orthodontists. The orthodontists were asked to review the records and formulate a comprehensive diagnosis and treatment plan. Once they had completed the diagnosis and treatment plan, the plaster models were introduced with all the other records. They were then asked to re-evaluate their diagnosis and treatment plan to see if having the models would change any diagnostic or treatment criteria. They found that none of the treatment plans had changed after the study models had been introduced and concluded that the use of plaster models for adequate diagnosis and treatment planning may be questionable.13


Advances in technology have created other opportunities to avoid alginate impressions and plaster models. Many studies have evaluated the reliability and validity of digital models, intraoral scanning, and cone beam computed tomography scanning compared to traditional plaster models for diagnosis and treatment planning.5,6,7,8,9,10,13,14 The consensus of these studies supports the use of digital alternatives. The American Board of Orthodontics also accepts these digital versions in place of traditional plaster models for the pretreatment record of board certification. They still, however, require plaster models for the final record. Parenthetically, the AAO, in a recent publication of the The Bulletin, responded to the question “Can digital photos be taken instead of traditional models?” by stating “The AAO does not have an official position regarding this issue.” This statement seems to be contradictory to the position they take in their official guidelines for “Patient Records and Record Keeping.”4 Regardless, the evidence is still lacking in support of any form of pretreatment models to enhance diagnosis and treatment planning.

In the present study, 57.31% of orthodontists that responded said that one of the main reasons they take pretreatment study models is for legal reasons. Historically, this has been true. Dr. Laurance Jerrold15 stated, “Dental records are supposed to be an accurate reflection of your conversations with the patient, the treatment rendered, recommendations made, etc.” However, with the improvement of digital photography, pretreatment intraoral and extraoral photographs can adequately document the patients’ condition prior to treatment. It could be argued that more information about a patients’ pretreatment condition can be derived from quality photographs than digital or plaster models because they show archform, crowding, periodontal condition, any gross carious lesions, pre-existing white spot lesions, malocclusion, extraoral asymmetry, and profile. With the AAO making the statement — “Pretreatment unaltered diagnostic records for comprehensive orthodontic treatment should include the following to establish a baseline for documenting treatment and/or growth changes: Dental casts (or digital models) to assess the inter-arch and intra-arch relationship of the teeth, to help determine arch length and width requirements, and to assess arch symmetry”3 — may make it legally difficult to justify not taking pretreatment study models. By saying that pretreatment dental casts or study models “should” be used is essentially discrediting some of AAO’s members who choose not to take pretreatment study models on all patients.


The results of this survey demonstrate the wide-ranging views on utilizing study models as a pretreatment record.

  • It was reported that 67.69% of orthodontist are currently taking pretreatment study models (digital or plaster) on all patients.
  • 66.54% of orthodontists cited better diagnosis as a reason for taking study models, while 57.31% also said they take pretreatment study models for legal reasons.
  • 29.23% of responding orthodontists strongly agreed that having pretreatment study models was important to making treatment decisions, while 25.77% strongly disagreed that having pretreatment study models was important to making treatment decisions.
  • 71.54% of those who responded to this survey have been in practice for longer than 20 years.

Decisive scientific evidence needs to be established for the recommendation that orthodontic pretreatment study models should be taken on all orthodontic patients.

1. Lightheart KG, English JD, Kau CH, Akyalcin S, Bussa HI Jr, McGrory KR, McGrory KJ. Surface analysis of study models generated from OrthoCAD and cone-beam computed tomography imaging. Am J Orthod Dentofacial Orthop. 2012;141(6):686-693.
2. Schulman M. JCO interviews Martin L. ‘Bud’ Schulman on success through sharing. Interview by Eugene L. Gottlieb. J Clinical Orthod. 2002;36(10):569-578.
3. Gladwell M. Blink: The Power of Thinking Without Thinking. New York: Little, Brown and Company;2005.
4. Patient Records and Record Keeping, available at
5. Stevens DR, Flores-Mir C, Nebbe B, Raboud DW, Heo G, Major PW. Validity, reliability, and reproducibility of plaster vs digital study models: comparison of peer assessment rating and Bolton analysis and their constituent measurements. Am J Orthod Dentofacial Orthop. 2006;129(6): 794-803.
6. Wiranto MG, Engelbrecht WP, Tutein Nolthenius HE, van der Meer WJ, Ren
7. Y. Validity, reliability, and reproducibility of linear measurements on digital models obtained from intraoral and cone-beam computed tomography scans of alginate impressions. Am J Orthod Dentofacial Orthop. 2013;143(1):140-147.
8. Okunami TR, Kusnoto B, BeGole E, Evans CA, Sadowsky C, Fadavi S. Assessing the American Board of Orthodontics objective grading system: digital vs plaster dental casts. Am J Orthod Dentofacial Orthop. 2007;131(1):51-56.
9. Whetten JL, Williamson PC, Heo G, Varnhagen C, Major PW. Variations in orthodontic treatment planning decisions of Class II patients between virtual 3- dimensional models and traditional plaster study models. Am J Orthod Dentofacial Orthop. 2006;130(4):489-491.
10. Cuperus AM, Harms MC, Rangel FA, Bronkhorst EM, Schols JG, Breuning KH. Dental models made with an intraoral scanner: a validation study. Am J Orthod Dentofacial Orthop. 2012; 142(3):308-313.
11. Han UK, Vig KW, Weintraub JA, Vig PS, Kowalski CJ. Consistency of orthodontic treatment decisions relative to diagnostic records. Am J Orthod Dentofacial Orthop. 1991;100(3):212-219.
12. Jerrold L. Litigation, legislation, and ethics. Dental records as evidence. Am J Orthod Dentofacial Orthop. 2000;118(2):241-242.
13. Proffit WR, Fields HW, Sarver DM, eds. Contemporary Orthodontics. 4th edition. St. Louis, MO:Mosby; 2007:192.
14. Callahan C, Sadowsky PL, Ferriera A. Diagnostic Value of Plaster Models in Contemporary Orthodontics. Seminars in Orthodontics. 2005;11:94-97.
15. Rheude B., Sadowsky P.L., Ferriera A., Jacobson A., “An evaluation of the use of digital study models in orthodontic diagnosis and treatment planning” Angle Orthod. 2005;75(3):300-304.
16. Miles PG, Rinchuse DJ, Rinchuse DJ, eds. Evidence-Based Clinical Orthodontics. Chicago, IL: Quintessence Publishing Co. Inc.; 2012.
17. Jerrold L. Litigation, legislation, and ethics. Dental records as evidence. Am J Orthod Dentofacial Orthop. 2000;118(2):241-242.

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