The American Board of Orthodontics is constantly striving to make the clinical examination a fair, accurate, and meaningful experience for examinees. In an effort to enhance the reliability of the examiners and provide the examinees with a tool to assess the adequacy of their finished orthodontic results, the Board has established a Model Grading System to evaluate the final dental casts and panoramic radiographs. This scoring system was developed systematically through a series of four field tests over a period of five years. The Board instituted the model and radiographic portions of the Model Grading System and it has been used to grade these portions of the examinee clinical case reports since 1999.

In an effort to assist examinees with the selection of their cases, the Board has made this Model Grading System available to all examinees. The Board encourages examinees to score their own case reports with this scoring system to determine if they meet Board standards. For your convenience, the ABO has available for purchase a Calibration Kit to assist you. This kit contains three sets of pre-measured casts with scoring keys, the grading system instructional manual, and a measuring gauge.

In 1994, The American Board of Orthodontics began investigating methods of making the clinical examination more objective. Since a major emphasis has always been placed on the final occlusion, the first efforts were directed at developing an objective method of evaluating the dental casts and intraoral radiographs.

In the past, several indices have been used to evaluate the outcome of orthodontic treatment.^1,2,3,4 Generally, these indices compare pretreatment and posttreatment records to determine the quality of the final result. However, these indices are not precise, and the validity and reliability of these indices has not been established. The Occlusal Index⁵ has also been used to determine treatment quality. However, this method is tedious, and the system is more appropriate for scoring pretreatment rather than posttreatment records.

In 1987, the PAR Index⁶ (Peer Assessment Rating) was developed to assess an occlusion at any stage of development. Over 200 dental casts representing various pretreatment and posttreatment stages of occlusion were used to establish this index. The PAR Index has good reliability and validity, however this measuring system is not precise enough to discriminate between the minor inadequacies of tooth position that are found in ABO case reports. Therefore, an ABO committee was formed in 1994, to begin field testing precise methods of objectively evaluating posttreatment dental casts and panoramic radiographs.

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