Since its inception in 1929, the American Board of. Comparison of prospectively and retrospectively selected American Board of Orthodontics cases

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1 ONLINE ONLY Comparison of prospectively and retrospectively selected American Board of Orthodontics cases Blair H. Struble a and Greg J. Huang b Bend, Ore, and Seattle, Wash Introduction: In this study, we compared the pretreatment conditions, treatment characteristics, and orthodontic outcomes of 3 groups of subjects selected for the American Board of Orthodontics (ABO) phase III clinical examination. One group was selected retrospectively by graduating residents just before their graduation. The 2 prospective groups were treated at separate institutions. The students at 1 institution were not aware that these patients would be potential ABO cases (prospective, blinded), but the students at the second institution were aware that these subjects would serve as their pool of potential patients for the ABO examination (prospective, unblinded). In addition to comparing the 3 groups, all cases were categorized as passing or failing based on their total objective grading system (ABO-OGS) score to assess the ABO-OGS criteria that were the most challenging to meet. Methods: Chart histories and orthodontic dental casts (pretreatment and posttreatment) were collected for 133 subjects. Information regarding demographics, initial malocclusion type, treatment modality, treatment duration, appointment frequency, and missed appointments were collected from chart histories. Pretreatment dental casts were evaluated by using the discrepancy index; the index of complexity, outcome, and need; and the peer assessment rating. Posttreatment dental casts were evaluated with the peer assessment rating and the ABO-OGS. Results: The only significant pretreatment characteristic with predictive power for favorable orthodontic outcome was Angle Class I (3.1 odds ratio for passing the ABO-OGS) compared with the Class II subjects. The prospective unblinded group received more extraction and headgear therapy than did the other groups. The retrospective group had significantly lower total ABO-OGS posttreatment scores and a higher passing rate compared with the prospective groups. Conclusions: Angle Class I malocclusions appear to have some advantage for achieving passing ABO-OGS scores, as does the retrospective selection of cases. Successful board certification appears difficult to accomplish based on a prospective model for orthodontic graduate residents. New graduate candidates might be at a disadvantage compared with traditional candidates because they often cannot take advantage of the posttreatment settling phase. Alignment, marginal ridges, and occlusal contacts appear to be where most points are deducted in the evaluation of ABO-OGS certification cases. (Am J Orthod Dentofacial Orthop 2010;137:6.e1-6.e8) Since its inception in 1929, the American Board of Orthodontics (ABO) has striven to certify as many practicing orthodontists as possible and elevate the standards of the practice of orthodontics. 1,2 When the percentages of board-certified orthodontists were 13% to 17% in the late 1970s, the board began efforts to increase the numbers of board-certified orthodontists. 1 In 2001, the ABO began actively pursuing the idea and the feasibility of certifying graduating orthodontic residents in the resident clinical outcomes study, or the pilot study (PS). This led to a 4-year collaborative project between the ABO and 16 American orthodontic a Private practice, Bend, Ore. b Chair, Department of Orthodontics, University of Washington, Seattle. The authors report no commercial, proprietary, or financial interest in the products or companies described in this article. Reprint requests to: Greg J. Huang, 1959 NE Pacific Street, D-569, Health Sciences Building, Box , Seattle, WA ; , ghuang@u. washington.edu. Submitted, December 2008; revised and accepted, May /$36.00 Copyright Ó 2010 by the American Association of Orthodontists. doi: /j.ajodo graduate programs accredited by the Commission on Dental Accreditation. 3,4 This project investigated whether orthodontic residents could provide start-tofinish treatment for 6 patients with ABO-quality results. At its inception, this PS was designed so that cases would be prospectively identified at the time of patient assignment, and residents, faculty, and patients at the participating programs would be aware of this PS designation. Orthodontic program directors at the participating institutions were asked to prospectively designate 12 patients for each incoming 2002 resident, 6 of whom would be presented to the board after treatment. Participating orthodontic residents would treat the patients, from banding to debanding, and be eligible to present the cases to the ABO to earn a 10-year time-limited certificate. Sixteen graduate orthodontic programs in the United States agreed to participate in the PS. Only 1 orthodontic program agreed to participate under the requirement that all persons involved in the treatment would be blinded to the designation of the prospectively selected PS patients. This method was chosen to prevent any 6.e1

2 6.e2 Struble and Huang American Journal of Orthodontics and Dentofacial Orthopedics January 2010 differential treatment of the PS subjects.the subjects at the other 15 programs were treated in an unblinded fashion, so that residents, faculty, and patients knew they were participating in the PS. During the PS, the study protocol was altered. The participant was allowed to present 6 cases for certification that included only 1 from the previously selected 12 that were prospectively designated. An incentive of a 15-year time-limited certificate was offered to residents presenting all prospectively selected PS cases, and 12% of PS examinees successfully earned this 15-year certificate. 5 The PS concluded in February 2006, when 50 participating orthodontic residents attended the ABO Clinical Examination. Forty-five candidates successfully obtained ABO certification, for a pass rate of 90%. This compared with 33 traditional candidates passing the examination at a rate of 85%. Therewas a mean difference of 2.38 ABO-OGS points for passing cases between the resident and the traditional examinees in the PS. The board concluded that the cases presented had sufficient complexity, with an average discrepancy index (DI) score of for the student cases, compared with an average DI score of for the regular examinees. The PS participants presented 422 cases, of which 58% were from the original prospectively selected PS group. 5 The board believed that this result positively affirmed that residents could treat to ABO standards during their orthodontic graduate programs. As a result, the board has now instituted new certification guidelines for recent graduates. 4 The new certification process has provided the impetus for graduate programs to self-evaluate their patient populations and the quality of orthodontic treatment provided in each residency program. In this study, we aimed to determine, with the aid of the DI; the peer assessment rating (PAR); the index of treatment complexity, outcome, and need (ICON); and the ABO objective grading system (ABO-OGS), whether there were significant differences in pretreatment conditions, treatment characteristics, and orthodontic treatment outcomes between ABO cases selected by using the 3 methods. We determined whether any pretreatment characteristics had predictive value in determining the orthodontic treatment quality outcome. Additionally, we categorically compared the ABO points deducted for failing vs passing cases, to determine which intraoral locations were the most difficult for the entire study sample. MATERIAL AND METHODS All study procedures were approved by the institutional review board at the University of Washington. The sample consisted of complete chart histories and dental casts (pretreatment and posttreatment) of all subjects. The sample comprised 3 groups. Groups 1 (retrospectively selected) and 2 (prospective blinded) were collected from the retention archives of a graduate orthodontic program participating in the PS. Group 3 (prospective unblinded) was collected from another graduate orthodontic program participating in the PS. No exclusion criteria were defined to prevent patients from participating in the study, as was the case with the initial PS guidelines. Patients were included irrespective of age, sex, race, or orthodontic problem if they were nonsyndromic and comprehensive orthodontic treatment was planned. The ABO stipulated that cases should be representative of a cross section of clinical problems and of adequate difficulty to represent the resident s ability to diagnose and treat orthodontic patients in the original PS guidelines. 5 When records were collected for this study, subjects were excluded if they were still in active orthodontic treatment, had incomplete records, had transferred treatment outside the assigned graduate clinic, or had never started treatment after the prospective PS designation. According to these criteria, 49 records were initially collected for group 1, which included subjects who were retrospectively selected by the graduating residents (classes of ) to be used in a simulated ABO examination. Two subjects were excluded from this group because of incomplete records, leaving 47 subjects in group 1. Group 2, the prospective blinded group, was prospectively selected to be part of the PS, and their study participation was concealed from all persons involved in the orthodontic treatment. Group 2 initially contained 57 subjects, but 16 were excluded based on the exclusion criteria, leaving 41 subjects. Group 3 records were gathered from another institution that treated patients in a prospective unblinded fashion. All persons involved (faculty, residents, patients) were aware of the PS designation. Group 3 started with 50 subject records, but 5 were excluded, leaving 45 prospective unblinded subjects. For the reasons outlined above, 23 subjects were excluded from the entire subject sample. All subject materials were deidentified and labeled with an identification number to facilitate investigator blinding. Subject records consisted of chart histories, and pretreatment and posttreatment dental casts. Chart histories were reviewed to gather information about demographics, initial malocclusion, treatment type, treatment duration, frequency of appointments, and missed appointments during active orthodontic treatment. In a few cases, phase 1 treatment had previously been

3 American Journal of Orthodontics and Dentofacial Orthopedics Struble and Huang 6.e3 Volume 137, Number 1 provided before the PS. In these circumstances, only information from the comprehensive phase of treatment was collected for these patients. This protocol is consistent with the ABO s evaluation of 2-phase patients in traditional board examinations. Pretreatment dental casts were scored by using the DI, PAR, and ICON by 2 calibrated, independent examiners. Posttreatment dental casts were scored by 2 examiners using the PAR, ICON, and ABO-OGS The radiographic component of the ABO-OGS index was excluded, because many patients had no posttreatment panoramic radiographs. Additionally, numerous studies have questioned the usefulness of panoramic radiography to assess root parallelism because of inherent image distortion, especially in premolar extraction sites. 11,12 The ABO-OGS scores were adjusted based on average PS radiographic deductions to account for this exclusion. The pretreatment and posttreatment casts from each site were combined, deidentified, assigned identification numbers, and measured in random order. Two investigators measured all dental casts independently, and the mean score was used unless significant differences were noted in the scores (weighted PAR, 5 points; weighted ICON, 9 points; ABO-OGS, 4 points). When differences were greater than these values, the dental casts were rescored by consensus, and the consensus score was used. Twenty-one (15.8%) cases had to be rescored by consensus. To determine intraexaminer error, 10 casts were rescored later by each examiner. Intraexaminer error was evaluated by using the intraclass correlation coefficient for all examiners involved in the study (Table I). Pretreatment conditions and treatment characteristics were assessed and compared both qualitatively and quantitatively. These scores were compared with posttreatment conditions as assessed by the PAR, ICON, and ABO-OGS to determine treatment changes and the quality of orthodontic treatment between the groups. Descriptive statistics (means, standard deviations, and ranges) were calculated for pretreatment DI and ICON, pretreatment and posttreatment PAR, and posttreatment ABO-OGS scores. Descriptive statistics were also performed for patient demographics, initial malocclusion (type and severity), treatment type, treatment duration, and number of orthodontic appointments. Analysis of variance (ANOVA) was used to test for differences in continuous variables between the groups. Pairwise between-group comparisons were carried out when ANOVA indicated differences between the groups. The Bonferroni adjustment to the significance level was used to correct for multiple comparisons in post-hoc analyses. This correction was Table I. Inraobserver error Intraclass correlation coefficient Examiner 1 (BHS) Examiner 2 (CJ) Examiner 3 (SH) ICON PAR ABO-OGS BHS, Blair H. Struble; CJ, Cameron Jolley; SH, Sara Haley. applied to prevent inflation of the type 1 error rate caused by multiple comparisons. 13 When the sample was divided into passing and failing cases, the average scores were compared with t tests. Logistic regression was used to determine whether any pretreatment variables could be used as reliable predictors of successful board-quality treatment. A stepwise model-building algorithm was used to identify a subset of available covariates that was highly predictive of successful board-quality treatment. The statistician was blinded to treatment group identification until the analyses were completed. For all analyses, the levels of significance were set at P \0.05 and P \0.017 when the Bonferroni adjustment was performed. RESULTS The 3 treatment groups were similar with respect to demographics and pretreatment characteristics (Table II). All groups had similar sex ratios, with more females than males. There were similar percentages of white patients in the groups. Group 3 had no Asian or Hispanic subjects and more black subjects (26.7%) compared with groups 1 and 2. There were more Class I subjects (53.2%) and fewer Class II subjects (38.3%) in group 1 (retrospectively selected group) compared with the other groups. There were no significant differences between the groups regarding subject age at initial records, start of treatment, or end of treatment (Table III). The group 3 subjects had a younger average pretreatment age, but this was most likely because several older adults were included in groups 1 and 2. When age medians and ranges were examined, all 3 groups were similar at initial records. When average length of treatment was assessed, there was a significant difference between the groups, P With the Bonferroni adjustment for multiple comparisons, group 2 had a statistically significant increase in average length of treatment (31.3 months) compared with both group 1 (25.0 months, P ) and group 3 (25.1 months, P ). Likewise, there was a significant difference

4 6.e4 Struble and Huang American Journal of Orthodontics and Dentofacial Orthopedics January 2010 Table II. Demographics, pretreatment conditions, and treatment Group Retrospective Prospective blinded Prospective unblinded Total Ethnicity White 35 (74.5%) 33 (80.5%) 32 (71.1%) 100 (75.2%) Asian 8 (17.0%) 2 (4.9%) (7.5%) Hispanic 1 (2.1%) 4 (9.8%) (3.8%) Black 1 (2.1%) 1 (2.4%) 12 (26.7%) 14 (10.5%) Other 2 (4.3%) 1 (2.4%) 1 (2.2%) 4 (3.0%) Sex Male 21 (44.7%) 17 (41.5%) 18 (40.0%) 56 (42.1%) Female 26 (55.3%) 24 (58.5%) 27 (60.0%) 77 (57.9%) Angle classification Class I 25 (53.2%) 17 (41.5%) 16 (35.6%) 58 (43.6%) Class II 18 (38.3%) 23 (56.1%) 21 (46.7%) 62 (46.6%) Class III 4 (8.5%) 1 (2.4%) 8 (17.8%) 13 (9.8%) Malocclusion type Anterior crossbite 15 (32.0%) 5 (12.2%) 10 (22.2%) 30 (22.6%) Posterior crossbite 6 (12.8%) 9 (22.0%) 4 (8.9%) 19 (14.3%) Deepbite 6 (12.8%) 7 (17.1%) 8 (17.8%) 21 (15.8%) Missing teeth 2 (4.3%) 5 (12.2%) 5 (11.1%) 12 (9.0%) Impactions 2 (4.3%) 2 (4.9%) 4 (8.9%) 8 (6.0%) Treatment modality Extractions 20 (42.6%) 18 (43.9%) 35 (77.8%) 73 (54.9%) Headgear 13 (27.7%) 12 (29.3%) 18 (40.0%) 43 (32.3%) Orthognathic surgery 4 (8.5%) 4 (9.8%) (6.0%) in the number of appointments, P However, when adjustments were made for multiple comparisons, only group 2 (28.6 appointments) reached statistical significance when compared with group 3 (24.4 appointments, P ). There was no significant difference in the numbers of missed appointments between the 3 groups. Group 3 had more subjects receiving extraction (77.8%) and headgear (40%) therapy during orthodontic treatment than those in groups 1 and 2 (Table II). Although it was difficult to quantify, it was known that some attending faculty in group 3 used treatment mechanics that included second-order tip-back bends. Attending faculty in groups 1 and 2 did not use this type of treatment. There was no significant difference between the 3 groups for any pretreatment cast analyses (DI, ICON, or PAR, Table IV). There was, however, a statistically significant difference between the groups for the posttreatment analyses (PAR and ABO-OGS). Group 1 (retrospective group) had statistically lower posttreatment PAR scores than did both prospectively selected groups (group 2, P ; group 3, P ). Likewise, for ABO-OGS scores, only the retrospective group 1 (16.2) was significantly different compared with groups 2 (23.1, P ) and 3 (28.4, P ). Because the radiographic root angulation component of the ABO-OGS was not scored in this study, the ABO s passing score of 26 was reduced to 23 based on the mean root-angulation point deduction of 2.6 from the PS rounded to the nearest whole number. Based on this ABO-OGS pass-or-fail cutoff point, there were 4 (8.5%) failures in group 1 (retrospective), 19 (46.3%) in group 2 (prospective blinded), and 28 (62.2%) in group 3 (prospective unblinded). There were 2 significant outliers: a subject in group 2 was debonded preemptively because of significant decay and restorative needs, and a subject in group 3 was debonded with a less than ideal result because of concerns about periodontal bone loss in the mandibular anterior region. These subjects were included in the analyses to follow the intent-to-treat principle. When the entire sample was divided into subjects passing (#23 points) vs those failing (.23 points) the ABO-OGS, passing cases had significantly lower scores for all ABO-OGS categories except interproximal contacts (Table V). Failing cases had the greatest average point deductions in alignment (8.3), marginal ridges (5.4), and occlusal contacts (7.6). These areas added up to an average deduction of 21.3 points for failing cases. If these major point deductions had been avoided, the

5 American Journal of Orthodontics and Dentofacial Orthopedics Struble and Huang 6.e5 Volume 137, Number 1 Table III. Treatment timing ANOVA Retrospective Prospective blinded Prospective unblinded Group Mean Median Range SD n Mean Median Range SD n Mean Median Range SD n P Patient ages (y) Age at initial records Age at start of treatment Age at end of treatment Treatment timing Treatment length (months) * Number of * appointments Number of missed appointments *Denotes statistical significance. Table IV. Dental cast analysis ANOVA Retrospective Prospective blinded Prospective unblinded Mean Range SD n Mean Range SD n Mean Range SD n P Pretreatment analyses DI ICON Pretreatment PAR Posttreatment analyses Posttreatment PAR * ABO-OGS * *Denotes statistical significance. average failing total ABO-OGS score of 32.3 points would have been reduced to a passing score of 11.0 points. These categories were explored in greater detail to determine where these points were lost. A significant percentage of alignment deductions occurred for second molar-first molar, first molarsecond premolar, and canine-lateral incisor contacts (67.1%). The most problematic areas for marginal ridges were first molar-second premolar contact in the maxilla and second molar-first molar in the mandible. Overall, these areas accounted for 91.6% of the points lost in this category. Occlusal contact deductions occurred most commonly for second molar contacts and accounted for 55.2% of the points lost (Table VI). Marginal ridges and occlusal contacts are 2 areas that have been shown to significantly improve during a posttreatment settling period. 14 When the ABO weighting formula developed by Nett and Huang 14 was applied to the mean score for failing ABO cases in this study, the average failing score of 32.4 (excluding root angulation) was reduced by more than 11 points to 21.0 points. Most dental casts evaluated in this study were taken at debanding. It is likely that, if a settling period had been allowed, many failing scores would have improved to passing ABO-OGS scores. When the entire sample was examined by Angle classification, there was nearly equal distribution in each class for passing and failing cases, excep for Class I subjects. The percentage of passing subjects in the Angle Class I category was much larger than for the Class II and Class III groups (Table VII). Based on these findings, a stepwise model-building procedure was used to construct a logistic regression model for the probability of passing (adjusted ABO-OGS #23) for the subjects in groups 2 and 3. Group 1 (retrospective) was not included in the model

6 6.e6 Struble and Huang American Journal of Orthodontics and Dentofacial Orthopedics January 2010 Table V. Pass vs fail ABO-OGS comparison Pass Fail Mean SD n Mean SD n P ABO-OGS categories Alignment * Marginal ridges * Buccolingual inclination * Overjet * Occlusal contacts * Occlusal relationship * Interproximal contacts Total * *Denotes statistical significance. building because inclusion in this group was such a strong predictor for success that it tended to overshadow any other possible predictors. Variables considered in this procedure included group, ethnicity, sex, age at start of treatment, length of treatment, number of appointments, number of missed appointments, classification, extraction therapy, use of headgear, posterior crossbite, deep overbite, missing teeth, and impacted teeth. The only variable that showed a statistically significant predictive power was a pretreatment Class I malocclusion as compared with Class II. A Class I subject had a 3.1 odds ratio for obtaining a passing ABO-OGS score than a Class II subject (P ; 95% CI, ). Pretreatment Class III malocclusion was also identified by the model-building procedure as highly predictive of obtaining a passing score. However, this association failed to achieve statistical significance because of the small number of subjects in the Class III malocclusion group. DISCUSSION In comparing the 3 groups in this study, the subjects were generally equal in sex, age, malocclusion type, and malocclusion severity (measured by the DI, ICON, and PAR) before treatment. However, there were more Class I patients in the retrospectively selected sample. This might indicate that, although there might be other malocclusion problems that contributed to higher severity scores, a proper anteroposterior relationship before treatment can be a positive predictor of a subject s likelihood of posttreatment orthodontic success as measured by the ABO-OGS. The predictive model derived from this study supported this idea in showing that Class I subjects had an odd ratio of 3.1 for passing the ABO-OGS compared with Class II subjects. Because the subject groups were similar before treatment, perhaps the differences during orthodontic Table VI. Point deduction percentages by intraoral location for alignment, marginal ridges, and occlusal contacts Alignment (% of total points) Marginal ridges (% of total points) Second molar-first molar First molar-second premolar Second premolar-first premolar First premolar-canine Canine-lateral incisor Lateral incisor-central incisor Midline Occlusal contacts Buccal Lingual Distal second molar Mesial second molar Distal first molar Mesial first molar Second premolar First premolar treatment might help to explain the discrepancy in posttreatment results between them. The prospective blinded group had a significantly longer treatment time (31.3 months) than the retrospective (25.0 months) and prospective unblinded (25.1 months) groups, P This is not surprising, since only the prospective blinded group providers were unaware of the potential ABO-OGS evaluation of their patients, and assigned students were under no pressure to finish treatment. Most prospective blinded subjects were treated by more than 1 resident. Also, several students could have treated the retrospectively selected patients. On the other hand, the students treating the prospective unblinded group knew that they must complete the PS cases to present them to the ABO and were given a certain date by which appliances must be removed. This was done to allow settling before the student graduated, so that an additional set of posttreatment dental casts could be obtained for the ABO examination. If treatment times between the retrospective (group 1) and prospective unblinded (group 3) groups were almost identical, how do we explain the significant discrepancy in posttreatment ABO-OGS pass rates between these groups? The retrospective group had more Class 1 subjects, whereas the prospective unblinded group received more headgear and extraction therapy. In addition to these treatment techniques, some prospective unblinded treatment providers incorporated second-order tip-back bends for their patients. This orthodontic technique resulted in many marginal-ridge and occlusal-contact ABO-OGS point deductions if the cases were evaluated at debanding.

7 American Journal of Orthodontics and Dentofacial Orthopedics Struble and Huang 6.e7 Volume 137, Number 1 Table VII. Pass vs. fail breakdown by Angle s classification Passing cases Failing cases Class I 42 (72.4%) 16 (27.6%) Class II 33 (53.2%) 29 (46.8%) Class III 7 (53.8%) 6 (46.2%) Many group 3 subjects were debanded several months before graduation to allow settling before impressions were taken for posttreatment dental casts. This difference in orthodontic treatment technique and philosophy might help to explain the differences in the ABO-OGS mean scores, since most dental casts for the prospective unblinded group were evaluated at debanding rather than after posttreatment settling. 14,15 The application of the ABO weighting formula to our samples showed that ABO-OGS scores tended to improve after active orthodontic treatment. 14 Most dental casts evaluated in this study were taken at debanding. It is likely that, if a settling period had been allowed for these cases, many failing scores would have improved to passing ABO-OGS scores. When this formula was applied to the average ABO-OGS scores for group 3 (with the lowest ABO passing rate), there was an 8.6- point reduction in average ABO-OGS score from 28.4 to 19.8 before the root-angulation category was included. This represented a significant improvement in scoring and reduced an average failing score for this group to an average passing score. The topic of whether to retrospectively or prospectively select cases for ABO certification was altered during the development and evolution of the current certification system. 5 It seems likely that patients treated prospectively by unblinded practitioners would receive additional attention compared with an average orthodontic patient. On the other hand, retrospectively selected patients might include better treatment cooperators and those with more favorable growth and possibly less complex malocclusions. A retrospective system of selection for board certification treats the entire orthodontic patient population as potential cases for board certification and tends to equalize the standard of care to all patients, compared with a prospectively unblinded system. The ABO s decision to alter the PS protocol from a prospective designation to a largely retrospective selection model seems justifiable based on our results. Collectively, about 50% of the subjects in the 2 prospective groups of this study did not have passing ABO-OGS scores. Group 2 had a much longer average treatment time, indicating that these patients often had several students during their treatment. This would disqualify them as potential ABO patients because the board requires all cases to be treated entirely by the ABO candidate. Our results might indicate that successful board certification based on a prospective model for orthodontic graduate residents is difficult to accomplish. Even though the providers were aware of the subject s PS designation in the prospective unblinded group, this group had a higher ABO-OGS failure rate than did the prospective blinded group. The difference in failure rates between the 2 prospective groups could be explained in several ways. First, the blinded group had a significantly longer mean treatment time and more appointments compared with the unblinded group. This period might have been important to accomplish final detailing of the occlusion. The prospective unblinded group had more extraction (77.8%) and headgear (40%) therapy. They also might have had second-order tip-back bends that often benefit from a period of settling after debanding for occlusal-contact and marginal-ridge problems to resolve. Most posttreatment dental casts for the entire sample were taken at debanding, and this could have been a significant disadvantage, especially to the prospective unblinded group. Finally, it is interesting to see which categories appeared to present the greatest challenge to treatment providers in this study. Alignment, marginal ridges, and occlusal contacts were the 3 categories with the greatest point deductions in all 3 groups. These mistakes occurred in categories previously reported by the ABO to be among those with the most problems in preliminary field tests. Second molars appeared to be a consistent problem in this sample, even though the median ages at start and end of treatment were approximately 14 and 16 years, respectively. Even at this age, when second molars should be fully erupted, they still present a significant challenge when evaluated with the ABO- OGS. Marginal ridges and occlusal contacts are both susceptible to improvement during the posttreatment settling phase. 15 This settling advantage was not always possible for resident examinees, who must complete certifcation cases in the time constraints of residency programs. Orthodontic residency programs interested in providing the best possible opportunities for their graduates to accomplish orthodontic certification should pay special attention to these controllable factors and ensure that patients are of an appropriate age with a fully erupted dentition. This study defined 3 groups. Group 1, the retrospectively selected group, indicated that we treat some patients to high standards, and we are good at identifying excellent results after treatment. Group 2 (prospective, blinded) represents a standard sample of university teaching cases during a specified time period, and, when there is no rush to complete treatment, it

8 6.e8 Struble and Huang American Journal of Orthodontics and Dentofacial Orthopedics January 2010 appears that about 50% of the cases could meet ABO standards. Group 3 (prospective, unblinded) indicated that prospective identification of 12 ABO subjects might be an insufficient number to meet the board s prior prospective pathway for new graduates, since the passing rate in this group was less than 50%. The major strengths of this study included blinded evaluation of a relatively large sample, several study sites, and patients who were treated during the same period of time. Additionally, the groups were relatively similar with respect to pretreatment conditions. Nearly all posttreatment dental casts were evaluated at debanding. Because graduating students might need to obtain final records before they leave their institutions, dental casts from this time accurately reflect what the students can present to the board. Therefore, this could be considered a strength of this study. On the other hand, posttreatment settling is likely to improve several ABO-OGS parameters, and the dental casts that were assessed in this study might underestimate the ABO passing rate if settling had been allowed to occur. 15 There were some differences in ethnicity, Angle classifications, and treatment modalities, and all of these might be limitations to this study. It was not possible to assess growth and compliance from the records we obtained, and these unknown factors could have influenced the outcomes. Finally, many factors contribute to determining the outcome of a treated patient, and, although the predictive model used in this study provides some insight into those factors, larger samples are needed to adequately address them. CONCLUSIONS 1. Class I subjects seem to have a distinct advantage (odds ratio, 3.1) over Class II subjects for achieving passing ABO-OGS scores. 2. It appears challenging to accomplish successful board certification with a prospective model for orthodontic graduate residents based on these results. 3. Candidates should pay special attention to the alignment, marginal-ridge, and occlusal-contact categories, especially regarding second molars, because these were the most problematic areas for all groups in this study. 4. New graduate examinees might have a disadvantage compared with traditional examinees, since they often do not have time to benefit from posttreatment settling. REFERENCES 1. Cangialosi TJ, Riolo ML, Owens SE Jr, Dykhouse VJ, Moffitt AH, Grubb JE, et al. The ABO s 75th anniversary: a retrospective glance at progress in the last quarter century. Am J Orthod Dentofacial Orthop 2004;125: Cangialosi TJ, Riolo ML, Owens SE Jr, Dykhouse VJ, Moffitt AH, Grubb JE, et al. The American Board of Orthodontics and specialty certification: the first 50 years. 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