Turkish Journal of Orthodontics
Original Article

Reporting Sample Size Calculation in Randomized Clinical Trials Published in 4 Orthodontic Journals


Department of Orthodontics, Universidad Científica del Sur School of Dentistry, Lima, Perú


Department of Orthodontics, University of Alberta, Edmonton, Alberta, Canada

Turk J Orthod 2021; 34: 214-219
DOI: 10.5152/TurkJOrthod.2021.21030
Read: 280 Downloads: 145 Published: 01 December 2021

Objective: The purpose of this study was to describe sample size calculations in randomized clinical trials (RCTs) published in four orthodontic journals. 

Methods: This cross-sectional study evaluated 142 RCTs published from 2015 to 2019 in the four journals with the highest impact factor in orthodontics according to SCIMAGO 2018 ranking. Two trained and experienced orthodontists assessed if the RCTs evaluated reported their sample size calculations, and if they adequately described the criteria for the calculations, including the level of significance, test power, precision or effect size (clinically relevant difference), and expected variability. The reporting of sample size calculation was considered adequate when the above four criteria were described. 

Results: We identified 120 publications (84.5%) reporting the sample size calculation, but only 70 (58.3%) fully described the above parameters. Inadequate calculation included failure to report the confidence level (ranging from 0% to 12.9%), test power (ranging from 0% to 20%), effect size (ranging from 0% to 22.5%) and expected variability (ranging from 22.6% to 80%). According to the journal, some parameters of sample size calculation were more frequently reported. 

Conclusion: RCTs published in four leading orthodontic journals frequently do not report the parameters used for sample size calculations. 

Cite this article as: Calderon-Augusto M, Flores-Mir C, Arriola-Guillén LE. Reporting sample size calculation in randomized clinical trials published in 4 orthodontic journals. Turk J Orthod. 2021; 34(4): 214-219.

EISSN 2148-9505