An Overview of the American Board of Orthodontics Certification Process

Introduction

The American Board of Orthodontics (ABO) was founded nearly 90 years ago in 1929 as the first American specialty board in the field of dentistry. The ABO, in affiliation with the American Association of Orthodontists (AAO), is, in fact, the only orthodontic specialty board that is recognized by the American Dental Association. This special feature article will present an overview of the ABO certification process. Specifically, this article will review the examination’s components, a classic high-angle Class II growing patient case that successfully passed the ABO examination, the discrepancy index (DI) evaluation used to assess how difficult a case is, and the cast-radiograph (CR) evaluation used to assess how well a case is finished. Other than the details of the clinical case that successfully passed the ABO examination and the walkthrough of the case’s pre- and post-treatment scoring, much of the information presented in this special feature article can be found in further detail on the ABO website^[1] at https://www.americanboardortho.com.

Examination Components

To become board certified by the ABO, an orthodontist must successfully pass a written examination as well as a clinical examination. The written examination constitutes a comprehensive examination that evaluates multiple subject areas including the basic and applied biomedical sciences and various clinical concepts. Clinical concepts include, but are not limited to, orthodontic diagnosis and treatment planning, orthopedics and biomechanics, orthodontic materials and appliances, cephalometrics and temporomandibular disorders, as well as clinical case analyses.

After successful completion of the written examination, an orthodontist must pass the clinical examination, of which there are several components. The first is the Board Case Oral Examination (BCOE) which constitutes a board case presented by the ABO to the examinee. The BCOE assesses the examinee’s evaluation of the presented case and their consequent treatment plan. The second component is the Case Report Examination (CRE) which constitutes cases presented by the examinee to the ABO. The CRE presents a comprehensive evaluation of a variety of case records treated entirely by the examinee. The final component is the Case Report Oral Examination which constitutes an oral assessment of the examinee’s knowledge about the cases that they have presented during the CRE. Beginning in February 2019, however, the ABO will change the clinical examination into a scenario-based oral examination that does not require examinees to submit patient cases. Despite the change in the clinical examination format, the Discrepancy Index (DI) and the Cast-Radiograph (CR) evaluation, the two critical tools created by the ABO to assess case complexity and case outcome, respectively, will still be used and tested extensively.

One of the primary and important steps of the CRE is to measure case complexity. In other words, it is important to be able to assess how difficult the treated case is. To this end, the ABO has established a comprehensive DI system which systematically analyzes and scores every element of the selected case. Examinees must select a total of six cases for the CRE, and these six cases must meet specific criteria. All six cases must score a DI of ten or higher, of which three must score a DI of twenty or higher. Of the six cases, at least one must be treated with four quadrant extractions demonstrating proper management of the extraction sites. This case, treated without orthognathic surgery, is identified by the ABO as an extraction case. In addition to the extraction case, there must also be at least one case with bilateral end-to-end or greater Class II molar relationships where the final treatment results in bilateral Class I molar and canine relationships. This case, also treated without orthognathic surgery, is identified by the ABO as a Class II Case. Finally, no more than one of the six cases can be treated with orthognathic surgery, although a surgical case is not required for the ABO examination unlike the extraction case and the Class II Case. If an examinee decides to present a case treated with orthognathic surgery, it is identified by the ABO as a surgical case.

Discrepancy Index

The case presented in this article is an example of a high-angle Class II case treated by four bicuspid extractions that successfully passed the ABO clinical examination [Figure 1]. The DI score for this case was scored at 50 [Figure 2]. A complete description of the DI evaluation and measurement instructions can be found on the ABO website.^[1]

Close

Figure 1

Initial records and cephalometric tracing with American Board of Orthodontics measurements. Initial (a) photo composite, (b) panoramic radiograph, (c) lateral cephalogram, and (d) tracing with American Board of Orthodontics measurements

Export to PPT

Close

Figure 2

Discrepancy index form completely filled out

Export to PPT

As can be seen, the ABO DI includes a number of specific scoring instructions for the following categories: Overjet, overbite, anterior open bite, lateral open bite, crowding, occlusal relationship, lingual posterior crossbite, buccal posterior crossbite, cephalometrics, and other. The present case scored three points for overjet because the overjet, as determined between two antagonist anterior teeth that comprise the largest overjet when measured from the middle incisal edge of the more facially positioned maxillary tooth to the facial surface of the most lingual mandibular tooth, was between 5.1 and 7 mm. This case scored zero points for overbite because the overbite was <3 mm. Likewise, this case scored zero points for anterior open bite because there were no anterior teeth that were in an edge-to-edge relationship or greater. Similarly, zero points were scored for lateral open bite. Note that the ABO does not score points for teeth that are blocked out of the arch or not fully erupted.

This case scored seven points for crowding because the most crowded arch circumference between the first molars had crowding >7 mm. This case scored four points for occlusal relationship because the relationship was Class II end-to-end for both the left and right sides, scoring two points per side. When scoring occlusion, the ABO utilizes the Angle classification, and each side is scored individually. Zero points were scored for lingual posterior crossbite because there were no maxillary posterior teeth where the maxillary buccal cusp was lingual to the buccal cusp tip of the opposing mandibular tooth. Similarly, zero points were scored for buccal posterior crossbite because there were no maxillary posterior teeth in complete buccal crossbite.

Regarding cephalometrics, this case scored four points because the ANB angle was ≥6°. In addition, a total of 26 points were scored for the SN-MP angle. Two points were scored for the fact that the SN-MP angle was >38°, and then 24 points were further scored because the SN-MP angle was 12 full degrees >38°. As evidenced by the present case, many points can be scored for an extremely dolichofacial or brachyfacial patient. It is important to note that the ABO has specific criteria for construction of the mandibular plane when scoring points for cephalometrics [Figure 3]. According to the ABO, the mandibular plane constitutes a plane drawn from constructed gonion to menton. Constructed gonion is determined by the bisecting angle formed by a line tangent to the posterior border of the mandibular ramus and a line tangent to the inferior border of the body of the mandible. Specifically, constructed gonion is the landmark corresponding to the intersect point of the bisecting line and the outline of the mandible.

Close

Figure 3

Construction of mandibular plane. Top: The American Board of Orthodontics describes (a) “line tangent to the posterior border of the ramus,” (b) “line tangent to the inferior border of the body of the mandible,” and (c) “constructed gonion, determined by bisecting the angle formed by a line tangent to the posterior border of the ramus and a line tangent to the inferior border of the body of the mandible. Constructed gonion landmark is the intersect point of the bisecting line and the outline of the mandible.” Bottom: The final constructed mandibular plane used for cephalometric analysis

Export to PPT

Finally, this case scored six points in the other categories. Four points were scored for impacted teeth not including third molars at two points per tooth. In addition, two points were scored for a midline discrepancy of 3 mm or greater. In the other categories, any dental anomalies and abnormalities can be included which justify a greater DI score. These include, but are not limited to, supernumerary teeth, ankylosis of permanent teeth, missing teeth, significant spacing, tooth transpositions, skeletal asymmetry, and additional treatment complexities.

Treatment Plan

Regarding the patient’s treatment plan, despite her notable skeletal Class II relationship, the patient presented an end-on Class II malocclusion with mild-to-moderate proclination of the upper and lower incisors due to the hyperdivergent profile. Due to the patient’s extremely hyperdivergent profile, upper arch distalization was deemed contraindicated. As such, four first premolars were extracted. Upper and lower 6-6 were bonded with 0.022 preadjusted edge-wise appliances, and high-pull headgear was delivered for night-time wear. Posterior teeth were tied, and leveling and alignment was achieved with the sequential use of 0.014NiTi, 0.016NiTi, 0.016 × 0.022NiTi, 0.019 × 0.025NiTi, and 0.019 × 0.025SS. 7’s were bonded and the partially-impacted L7’s were uprighted using sectional 0.018NiTi and open-coil springs from L6 auxiliary tubes. One year into treatment, the patient reported that she could no longer wear the headgear, so full-time L-shape Class II elastics (3/16 inches, 6.0 oz) were used instead. Due to patient’s Quinceanera next month, treatment had to be terminated early. The occlusion was finished and detailed as much as possible, and appliances were removed. The patient was extremely satisfied with her overall treatment and results [Figure 4]. The superimposition of the initial and final cephalometric tracings is shown in Figure 5. Video instructions of evidence-based maxillary, mandibular, and cranial base superimpositions can be found on the ABO website^[1] at https://www.americanboardortho.com/orthodontic-professionals/about-board-certification/downloads-and-references.

Close

Figure 4

Final records and cephalometric tracing with American Board of Orthodontics measurements. Final (a) photo composite, (b) panoramic radiograph, (c) lateral cephalogram, and (d) tracing with American Board of Orthodontics measurements

Export to PPT

Close

Figure 5

Superimposition of the initial and final cephalometric tracings. Maxillary, mandibular and cranial base superimpositions on the top left, bottom left, and right, respectively

Export to PPT

Cast-radiograph Evaluation

Besides the case complexity as measured by the ABO through the DI, the other important step of the CRE is to measure the case outcome. In other words, it is critical to be able to assess how well the case was finished. To this end, the ABO has established a comprehensive CR evaluation which systematically analyzes every element of the selected case and its finished occlusion using the final dental casts and panoramic radiograph. Specifically, the ABO established a wide-ranging model grading system not only to improve examiner reliability when evaluating examinees but also to provide examinees with an objective method to evaluate their own cases.

A complete description of the CR evaluation and measurement instructions using the ABO ruler can be found on the ABO website at https://www.americanboardortho.com/orthodontic-professionals/about-board-certification/clinical-examination/case-report-preparation/CR-evaluation. A video demonstration on how to perform the CR measurements using the ABO ruler can be found on the ABO website^[1].

As can be seen, the ABO CR evaluation includes a number of specific scoring instructions for the following eight criteria: alignment/rotations, marginal ridges, buccolingual inclination, overjet, occlusal contacts, occlusal relationship, interproximal contacts, and root angulation [Figure 6]. To facilitate measurements of the casts for the aforementioned criteria, the ABO has designed a specific straight edge ruler called the ABO Measuring Gauge. This ruler measures 0.5 mm in thickness and measures 1 mm for each step [Figure 7]. Consequently, the ABO Measuring Gauge presents a reliable method to measure discrepancies in marginal ridge heights, buccolingual inclination, and more. A pictorial description of the CR measurements can be found on the ABO website at https://www.americanboardortho.com/media/1191/grading-system-casts-radiographs.pdf and serves as a good reference when reviewing the specific items below.

Close

Figure 6

Cast-radiograph evaluation completely filled out

Export to PPT

Close

Figure 7

American Board of Orthodontics measuring gauge, also known as the American Board of Orthodontics ruler

Export to PPT

The present case scored a total of 27 points for the CR evaluation. In general, the lower the score in the CR evaluation section, the more ideally the case was finished. Each tooth can score zero, one, or two points for each of the eight above criteria. No more than two points are scored for each tooth per criteria that deviates from ideal. In the alignment/rotation section, this case scored one point each for the maxillary second molars, and one point each for the mandibular first molars, totaling four points for the section. In particular, the ABO states the following: “If the mesial or distal alignment at any of the contact points is 0.50 mm to 1 mm deviated from proper alignment, 1 point shall be scored for the tooth that is out of alignment. If adjacent teeth are out of alignment, then 1 point should be scored for each tooth. If the discrepancy in alignment of a tooth at the contact point is >1 mm, then 2 points shall be scored for that tooth.”

In the marginal ridges section, this case scored three points in total. Ideally, in the upper and lower arches, the marginal ridges of adjacent posterior teeth must be within no more than 0.50 mm of each other. The canine-premolar contact is not scored in the section, and neither is distal of the mandibular first premolar. The ABO states the following regarding marginal ridges: “If adjacent marginal ridges deviate from 0.50 to 1 mm, then 1 point is scored for that interproximal contact. If the marginal ridge discrepancy is >1 mm, then 2 points shall be scored for that interproximal contact. The marginal ridge will be considered as the most occlusal point that is within 1 mm of the contact at the occlusal surface of adjacent teeth.”

In the buccolingual inclination section, this case scored four points in total. The buccolingual inclination of the posterior teeth is assessed using a straight edge, such as the ABO measuring Gauge, that is extended between the occlusal surfaces of the posterior teeth. In the mandibular arch, the straight edge should ideally contact the buccal cusps of contralateral mandibular posterior teeth, and the lingual cusps should be within 1 mm of the surface of the straight edge. As for the maxillary arch, the straight edge should ideally be in contact with the lingual cusps of the maxillary posterior teeth with the buccal cusps being within 1 mm of the straight edge surface. The ABO states the following regarding buccolingual inclination: “If the mandibular lingual cusps or maxillary buccal cusps are more than 1 mm, but <2 mm from the straight edge surface, 1 point shall be scored for that tooth. If the discrepancy is >2 mm, then 2 points are scored for that tooth.”

In the overjet section, this case scored six points in total. Overjet is assessed by examining the labiolingual relationship of the maxillary arch relative to the mandibular arch with the models fully articulated. The ABO states the following regarding overjet: “If the mandibular buccal cusps deviate 1 mm or less from the center of the opposing tooth, 1 point is scored for that tooth. If the position of the mandibular buccal cusps deviates more than 1 mm from the center of the opposing tooth, two points are scored for that tooth. In the anterior region, if the mandibular canines or incisors are not contacting lingual surfaces of the maxillary canines and incisors, and the distance is 1 mm or less, then 1 point is scored for each maxillary tooth. If the discrepancy is >1 mm then 2 points are scored for each maxillary tooth.”

In the occlusal contacts section, this case scored a total of 3 points. Ideally, the buccal cusps of the mandibular posterior teeth and the lingual cusps of the maxillary posterior teeth should be contacting the occlusal surfaces of the opposing teeth. The ABO states the following regarding occlusal contacts: “If the cusps are in contact with the opposing arch, no points are scored.  Do not score diminutive distolingual cusps of the maxillary first and second molars, nor lingual cusps of the mandibular first premolars. If a cusp is out of contact with the opposing arch, and the distance is 1 mm or less, then 1 point is scored for that tooth. If the cusp is out of contact and the distance is >1 mm, then 2 points are scored for that tooth.”

In the occlusal relationship section, this case scored a total of three points. The evaluation of this section is based on whether the occlusion has been finished in an angle Class I relationship where the maxillary canine cusp tip and the buccal cusp tips of the maxillary posterior teeth should align with or be within 1 mm of the opposing embrasures or contacts. The ABO states the following regarding the occlusal relationship: “If the maxillary buccal cusps deviate between 1 and 2 mm from the aforementioned positions, then 1 point shall be scored for that maxillary tooth. If the buccal cusps of the maxillary premolars or molars deviate by more than 2 mm from ideal position, then 2 points shall be scored for each maxillary tooth that deviates. In some situations, the posterior occlusion may be finished in either an Angle Class II or Class III relationship, depending on the type of tooth extraction in the maxillary or mandibular arches.”

In the interproximal contacts section, this case scored zero points. This determination is made by examining both casts from the occlusal surface, where the mesial and distal surfaces of the teeth should be in contact. The ABO states the following regarding interproximal contacts: “If >0.50–1 mm of interproximal space exists between two adjacent teeth, then 1 point is scored for that interproximal contact. If more than 1 mm of space is present between two teeth, then 2 points are scored for that interproximal contact.”

Finally, in the root angulation section, this case scored four points. Root angulation is evaluated using the final panoramic radiograph. Although a panoramic radiograph is not ideal, the ABO believes it provides a reasonable assessment of final root position wherein general all roots should be parallel to one another and oriented perpendicular to the occlusal plane. The maxillary and mandibular canines are not scored in this section. The ABO states the following regarding root angulation: “If a root is angled to the mesial or distal (not parallel) and is close to, but not touching, the adjacent tooth root, then 1 point is scored for each discrepancy (anterior, premolar, and/or molar areas). If the root is angled to the mesial or distal and is contacting the adjacent tooth root, then 2 points are scored for that tooth.”

Conclusion

The vision of the ABO (ABO), as a global leader in the orthodontic board certification process, is to set the standard of care for excellence in the field of orthodontics. By establishing a thorough DI form and CR evaluation and by making this information available to the public, the ABO strives to be both objective and transparent in allowing orthodontists to self-assess their finished cases. Finally, as evidenced by the ABO’s comprehensive examination components, the ABO seeks not only to set the highest standards of patient care but also to promote excellence in orthodontics and dentofacial orthopedics.