Outcomes of comprehensive fixed appliance orthodontic treatment: A systematic review with meta-analysis and methodological overview

Abstract

Objective: The aim of this systematic review was to assess the occlusal outcome and duration of fixed orthodontic therapy from clinical trials in humans with the Objective Grading System (OGS) proposed by the American Board of Orthodontics.

Methods: Nine databases were searched up to October 2016 for prospective/retrospective clinical trials assessing the outcomes of orthodontic therapy with fixed appliances. After duplicate study selection, data extraction, and risk of bias assessment according to the Cochrane guidelines, random-effects meta-analyses of the mean OGS score and treatment duration were performed and 95% confidence intervals (CIs) were calculated.

Results: A total of 34 relevant clinical trials including 6,207 patients (40% male, 60% female; average age, 18.4 years) were identified. The average OGS score after treatment was 27.9 points (95% CI, 25.3-30.6 points), while the average treatment duration was 24.9 months (95% CI, 24.6-25.1 months). There was no significant association between occlusal outcome and treatment duration, while considerable heterogeneity was identified. In addition, orthodontic treatment involving extraction of four premolars appeared to have an important effect on both outcomes and duration of treatment. Finally, only 10 (39%) of the identified studies matched compared groups by initial malocclusion severity, although meta-epidemiological evidence suggested that matching may have significantly influenced their results.

Conclusions: The findings from this systematic review suggest that the occlusal outcomes of fixed appliance treatment vary considerably, with no significant association between treatment outcomes and duration. Prospective matched clinical studies that use the OGS tool are needed to compare the effectiveness of orthodontic appliances.

Keywords: Meta-analysis; Orthodontics; Treatment duration; Treatment outcome.

Figure 1. Study flowchart showing the identification and selection of eligible studies.

ABO-OGS, Objective Grading System (OGS) proposed by the American Board of Orthodontics.

Figure 2. Summary of the risk of bias in the included studies.

Figure 3. Overall pooling for occlusal outcomes of fixed appliance (FA) treatment assessed using the Orthodontic Grading System proposed by the American Board of Orthodontics Mean Orthodontic Grading System scores and their corresponding 95% confidence intervals (CIs) for each included study are given as boxes with horizontal lines, respectively. The weighted pooled summary estimates with and their corresponding 95% CIs for the two subgroups or overall are given as diamonds. Horizontal lines at the diamonds represent the 95% prediction that gives a range of possible values to be clinically seen, while incorporating existing heterogeneity.

Figure 4. Overall pooling for the fixed appliance (FA) treatment duration in months. Mean treatment durations and their corresponding 95% confidence intervals (CIs) for each included study are given as boxes with horizontal lines, respectively. The weighted pooled summary estimates with and their corresponding 95% CIs for the two subgroups or overall are given as diamonds. Horizontal lines at the diamonds represent the 95% prediction that gives a range of possible values to be clinically seen, while incorporating existing heterogeneity.