Characterizing the orthodontic research literature: 2020.

Objectives: To characterize features of the current orthodontic literature.

Methods and materials: All research articles published in 2020 (N = 350) in the American Journal of Orthodontics and Dentofacial Orthopedics, The Angle Orthodontist, and the European Journal of Orthodontics were categorized on 48 features such as type of study (domain of generalization, subjects, and research design), analytical tools (statistical tests, power and normality of data, consistency of measurement, management of covariables, and corrections of multiple independent tests), and reporting characteristics. Consistency of the coding was high (κ > .990).

Results: The "most typical" article was a cohort study reporting multiple patient outcomes at a single treatment location. Soundness of analyses was uneven, with about half providing information on power or normality of the data and consistency of measurement. Few articles addressed covariables or adjusted for multiple tests of independent outcomes. Photos and flow charts were commonly used to explain methods, and results were presented in multiple formats. There was a clear association between design and reporting characteristics and type of study for systematic reviews, meta-analyses, and case reports. There were small but consistent differences across the three journals.

Conclusions: The quality of the orthodontic research literature has advanced at an uneven pace, and this review identifies areas that could be strengthened. Substantial gaps remain in achieving accepted standards for randomized controlled trials and opportunities exist for better understanding measures of effect through design and analysis using regression techniques to identify sources of variance.