Assessment Treatment Outcome By Model Analysis Using The American Board Orthodontic Objective Grading System (ABO-OGS)

Objectives:Based on the evaluation of the dental casts and panoramic radiographs of the cases who completed their orthodontic treatment in the Orthodontic Department of Shandong University Stomatology Hospital (SDU), by using the American Board of Orthodontics-Objective Grading System (ABO-OGS), the study was designed to establish the percentage each category could contribute to the total score; to assess the potential differences between ABO-OGS and six keys to normal occlusion; to explore the influences gender, extraction and different brackets may exert on the evaluation of orthodontic treatment outcome. Besides, through comparing the pass rate and potential pass rate of the cases collected in SDU to those in other researches, the extent to which the orthodontists holding domestic diplomas in the specialty of orthodontics may pass the ABO phase III clinical examination could be possibly established.Methods:87 cases were selected from the patients who finished their orthodontic procedures in SDU during the period ranging from 2007 to 2010. The standards for selection are listed as follows:(1) age:male>16, female>14;(2) orthodontic treatment is not included in the past medical history of the patients, who also received fixed orthodontic treatment; (3) the dental casts, panoramic radiographs and other basic documents of the cases are available; (4) the decision of finishing the orthodontic procedures was made out based on the satisfaction of both patient and orthodontist. The retrospective finished cases were then examined according to the ABO-OGS and assigned scores for each tooth in each category, a composite category score and a total score. After the cases were grouped by gender, extraction and brackets, t tests were employed to analyze the statistical discrepancies in total score and each category score between different groups. Finally, the pass rate (the number of cases scored below 20 in 87) and potential pass rate (the number of cases scored below 30 in 87) of the finished cases in SDU were compared to those of two other similar researches by means of Chi-square test.Results:The mean ABO-OGS score for the finished cases in SDU was 26.09±5.780, in which the category of alignment, occlusal contacts and marginal rideges contribute the most, while interproximal contacts made up the least percentage in the total score. The differences in the total scores between female and male cases, extraction and none extraction cases were of no statistical significance (P>0.05). The scores in interproximal contacts of extraction cases were statistically higher than those of none extraction cases (P<0.05), but the scores in occlusal contacts of the former group were found to be statistically lower (P<0.05) than those of the later. The cases with Roth brackets showed lower scores in the category of alignment than those with MBT brackets, whose scores in occlusal contacts were significantly lower than those of the Roth group. The pass rate of UB (P<0.01), IU (P<0.01) and the potential pass rate of UB (P<0.01) were statistically higher than those of SDU. However, no statistical significance was found between the potential pass rate of SDU and that of IU (P>0.05).Conclusion:(1) The finished cases in SDU demonstrated possible potential for passing ABO-OGS phaseⅢclinical examination. The categories of alignment, occlusal contacts and marginal ridges pose greatest impacts on the total ABO-OGS score of SDU cases.(2) The total ABO-OGS score seems not to be influenced by the gender and extraction. However, the category scores in alignment and interproximal contacts are related to extraction.(3) Although MBT brackets are more suitable than Roth brackets in adjusting the occlusal contacts, Roth backets may be more effective in helping the finished cases to score better in ABO-OGS.(4) The pass potential of the retrospective finished cases in UB and IU are generally greater than that in SDU, and the differences may be due to the inconsistency of case selection standards, number of cases, and treatment objectives between the three researches.