Clinical outcomes assessment of consecutively finished patients in a 24-month orthodontic residency: A 5-year perspective


The purpose of this study was to report on the clinical outcomes of a 24-month orthodontic residency.


One examiner scored 1019 consecutive pretreatment records and 714 consecutive posttreatment records annually over 5 years, using the American Board of Orthodontics discrepancy index and objective grading system.


The mean discrepancy index scores were 19.63, 14.84, 12.30, 15.72, and 15.39 for years 1 through 5, respectively. The mean objective grading system scores were 31.16, 34.79, 28.55, 26.28, and 22.11 for years 1 through 5, respectively. The residents’ completion rates for all cases were 58.9%, 60.5%, 82.7%, 74.4%, 78.2%, and 72.2% for years 1 through 5, respectively.


The establishment of an annual objective outcomes assessment benefited patients by improving objective grading system scores and reduced the number of transfers between residents (increased case completion rate), thus reducing faculty time for managing many transfer patients.

There are few scientific data available to support any specific length of graduate orthodontic education in terms of clinical education. The results derived from ongoing outcomes assessments of clinical treatment should provide a much better basis for curriculum planning, licensing, and certifications than relying on editorials, opinions, and anecdotal evidence. Ideally, such assessments should be broad based, include a variety of educational philosophies and treatment modalities, and evaluate all finished patients regardless of outcome.

As of 2005, only 1 program of any length, a 24-month program, had reported long-term scientific data based on the treatment results of consecutively finished patients. The goal of this study was to contribute to the rather small body of scientific data regarding clinical outcomes of postgraduate orthodontic education, by using the objective scoring methods of the American Board of Orthodontics (ABO).

Outcomes assessments allow private practitioners, university residents, and faculties to evaluate their results and raise the level of treatment outcomes. In 1998, the ABO introduced the objective grading system (OGS) for evaluation of completed treatment based on dental casts and panoramic radiographs. The discrepancy index (DI), was introduced by the ABO as a method to evaluate pretreatment complexity in 2004. The DI takes into account the initial dental casts, cephalometric values, and other pretreatment orthodontic records.

A 4-year collaborative project by the ABO and 15 graduate programs concluded that orthodontic residents can treat selected patients to an ABO standard within the time frame of graduate orthodontic programs ( Table I ). The project also showed that ABO resident examinees, on average, scored higher (poorer finish), on the OGS than traditional ABO examinees, but the scores were nevertheless of sufficient quality to satisfy ABO standards. In a pilot study of the DI, orthodontic resident cases selected with faculty guidance for inclusion were compared with those submitted by ABO candidates ( Table I ). It was concluded that the DI scores were “remarkably similar.”

Table I
IUSD, ABO-resident, ABO-orthodontist DI and OGS scores
IUSD ABO-resident ABO-orthodontist
Year 1 32.4 17.2 16.1
Year 2 33.1 16.96 21.98 21.84 17.44
Year 3 37.8
Year 4 28.66
Year 5 24.97
Year 6 22.42
Year 7 15.13
Year 8 14.99
Year 9 15.58

Superscript numbers refer to references.

The first published comprehensive study of a postgraduate orthodontic residency program was completed at Indiana University School of Dentistry (IUSD) and included the records of 521 consecutively finished patients; it reported average OGA scores of 32.4, 33.1, and 37.8 for 1998, 1999, and 2000, respectively ( Table I ). The report noted that longer treatment times were associated with poorer results (higher OGA scores), since problem patients were often transferred in the clinic.

IUSD initiated a number of curriculum changes to improve the outcomes and treatment efficiencies, having established a 3-year baseline in the 1998-2000 study. After implementation of these changes, IUSD reported the results for 437 consecutively finished patients: average OGA scores of 28.66, 24.97, and 22.42 for 2001, 2002, and 2003, respectively ( Table I ). Knierim et al stated, “We concluded that treatment outcomes improved as a result of the quality assessment process instituted after the baseline study.”

IUSD did not report pretreatment assessment scores (DI) on the patients from 1998 through 2003 but recently reported on case complexity by using the DI for 2004 through 2006. The mean DI scores were 15.13, 14.99, and 15.58, respectively ( Table I ).

Material and methods

In 2002, the Department of Orthodontics at the University of Detroit Mercy (UDM) initiated an annual assessment of all finished patients. At that time, the department had no objective data as to the complexity at the start of treatment or the quality of the outcomes.

A pilot assessment was completed in 2002. It was found that the patient management software of the dental school did not allow appropriate data collection for the started or finished patients. A number of curriculum changes and guidelines came about as a result of the pilot study. Residents’ patients were to be scored and distributed by using the DI, so that all residents would have an adequate variety for the ABO requirements. The department also established an 80% completion goal for all patients having comprehensive treatment.

The current curriculum at UDM is 24 months and consists of 6 unique clinical segments. Two clinical segments, early treatment in the mixed dentition and craniofacial and surgical, were not included in this study. The remaining 4 comprehensive treatment clinics included a standard edgewise (bracket with no first, second, or third order compensations) clinic, a modified straight-wire clinic, a straight-wire clinic based on the MBT prescription (3M Unitek, Monrovia, Calif) with some self-ligation, and a gnathologic clinic with the Innovation Roth prescription (GAC International, Bohemia, NY) with self-ligation.

Initial records of the patients in these 4 clinical segments were obtained before the arrival of the new residents. During the first week of residency, the patients were scored with the DI and distributed. All consecutive patients from the 4 comprehensive treatment clinics with records (unbroken and available) that could be scored were included regardless of outcome except for patients with anodontia, which do not score well with the OGS. The clinic uses plaster models, and the majority of the lateral headfilms and panoramic x-rays were the traditional analog type, except for some in year 5 that were generated from cone-beam digital scans.

Beginning in 2003, an inventory of each graduating resident’s patients with their statuses (in retention, active, transfer, or not being seen for various reasons) was gathered based on a manual review of the resident’s charts. The review was typically done in the last 2 weeks of the residency to ensure an accurate accounting of every patient. Although the residents were asked to score their own cases using the DI and OGA, an author (P.N.B.) also scored them annually; his data are presented. There was great leeway given in the scoring of the panoramic x-ray portion of the OGS, with only the most extreme occurrences marked down.

The residents and the author were calibrated annually with an ABO examiner. The author scored 10 unknown cases on 2 occasions 3 months apart to establish intraexaminer reliability. The intraexaminer correlation coefficient was .976.

Apr 13, 2017 | Posted by in Orthodontics | Comments Off on Clinical outcomes assessment of consecutively finished patients in a 24-month orthodontic residency: A 5-year perspective
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