[Agreement analysis of subjective evaluation of orthodontic treatment outcome].

Objective: To investigate the agreement of subjective evaluation of orthodontic treatment outcome and to analyze possible factors that may be related to it.

Methods: As a randomized clinical trial, with Angle's classification as a stratification factor, our study contained 48 cases with integrity data, which were randomly extracted from 806 orthodontic treatment cases in Peking University School and Hospital of Stomatology during July 2004 and August 2008, and gathered post-treatment study casts, cephalometrics and photographs of the 48 cases as the research subjects. Similarly with Angle's classification as a stratification factor, the 48 cases were randomly divided into 4 groups. According to the monomial and combined subjects, 12 clinicians were asked to act as the raters to rank the 12 cases in each group.

Results: Overall, there were 1 584 pairings between the raters in the examination of evaluation. The mean Spearman r was 0.565 3 ± 0.239 9. Grouping factor was related to the agreement of subjective evaluation (P<0.05). In the third trial item-Post-M+P, the correlations were the greatest among the judge-pairs (P<0.001). The other five items were at the same agreement level. The level of orthodontic treatment outcome was a factor that influenced the agreement level of subjective evaluation (P<0.05). The score stability of the patients, whose treatment duration was longer than 2.5 years, was significantly higher than that of the patients whose treatment duration was between 1.5 years and 2.5 years (P<0.05). The following factors, such as Angle's classification, age of patients and whether the teeth was extracted or not, were the insignificant factors (P>0.05).

Conclusion: The average correlations present a moderate agreement level. Grouping, experimental item, the length of treatment duration and the level of orthodontic treatment outcome are the factors that affect the agreement of subjective evaluation. Several factors including Angle's classification, age of patients and whether the teeth is extracted or not, do not affect the agreement of subjective evaluation.