Original article
Assessing the American Board of Orthodontics objective grading system: Digital vs plaster dental casts

https://doi.org/10.1016/j.ajodo.2005.04.042Get rights and content

Introduction: The purposes of this study were to determine whether the American Board of Orthodontics objective grading system (ABO OGS) can be assessed accurately from digital dental casts and whether there are statistical differences between digital and plaster dental casts in scoring the ABO OGS. Methods: Thirty posttreatment plaster dental casts were selected and scanned by OrthoCAD (Cadent, Carlstadt, NJ) to produce 30 corresponding digital dental casts. The plaster and digital casts were compared by using the criteria of the ABO OGS. Because the data were ordinal, a nonparametic statistical analysis was used. Results: The Wilcoxon test for paired samples showed significant differences between the plaster and digital casts for occlusal contacts, occlusal relationships, and total scores (P <.05). No significant differences were found for alignment, marginal ridges, overjet, and interproximal contacts. Buccolingual inclination was not included in this study because of inability to perform proper measurements with the OrthoCAD program. Mean differences of points deducted ranged from .03 point for marginal ridges to 5.07 points for the total score. The variable with the most points deducted related to occlusal relationships, and the fewest points were deducted for interproximal contacts. Conclusions: Based on this study, the current OrthoCAD program (version 2.2) was not adequate for scoring all parameters as required by the ABO OGS.

Section snippets

Material and methods

Thirty posttreatment plaster dental casts were selected from the University of Illinois at Chicago Department of Orthodontics. The dental casts were obtained from patients who had nonsurgical comprehensive orthodontic treatment with fixed appliances. The dental casts had to be in acceptable condition with all incisors, canines, at least 1 premolar, and the first and second molars bilaterally in both the maxillary and mandibular arches. No duplicates of dental casts were selected, and there was

Results

For intraexaminer reliability, the Wilcoxon test for paired samples showed no statistical differences for the plaster models (Table II) and the digital models (Table III). The mean differences for each variable and total score involving measurements taken at 2 separate times are shown for both the plaster and the digital models. The mean differences for each criterion and the total score were no greater than 0.05 points deducted for both plaster and digital model measurements.

With regard to

Discussion

When we compared the plaster and digital models, we found statistically significant differences for occlusal contacts, occlusal relationships, and total score. A major problem was encountered throughout the study that explains the differences for occlusal contacts and total score. When we performed the occlusal-contact measurements, the digital images of the maxillary and mandibular teeth overlapped each other. The result was an occlusal-contact measurement that measured the amount of vertical

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