Orthodontic trial outcomes: Plentiful, inconsistent, and in need of uniformity? A scoping review

The selection of appropriate outcomes that matter to both patients and operators is increasingly appreciated, with core outcome sets in clinical trials gaining in popularity. The first step in core outcome set development is the generation of a list of possible important outcomes based on a scoping literature review. Moreover, outcome heterogeneity is known to detract from the findings of systematic reviews and meta-analyses. The aim of this study was to identify the range of outcome domains and specific outcome measures in contemporary orthodontic research.

Multiple electronic databases were searched from December 31, 2012, to December 31, 2016, to identify clinical trials of orthodontic interventions, with no language restrictions. Abstracts, eligible full texts, and reference lists were screened, and all reported primary and nonprimary outcomes and methods of measurement were recorded.

The search identified 1267 abstracts, of which 189 full-text articles were retrieved, and 164 studies were included in the analysis. A total of 54 outcomes were identified and categorized into 14 outcome domains. The most frequently measured outcomes were patient-reported pain, periodontal health, tooth angulation/inclination changes, and treatment duration, followed by rate of tooth movement and skeletal changes. Outcomes that followed the overall course of treatment were assessed in only 14 studies.

Patient perspectives are increasingly being accounted for in orthodontic trials; however, there is little consistency in outcome selection among them. The identified list of outcomes will be used to inform a ranking exercise with service users and providers to establish an agreed core outcome set for future orthodontic clinical trials.