Publication pattern, study design, authors and countries involved in orthodontic RCTs – a bibliometric MEDLINE survey over the past 50 years

The objective of this study was to investigate the number and proportions, study design, journal publications, authors and countries involved in orthodontic randomised controlled trials (RCTs) over the past 50 years. A MEDLINE database search (Entrez PubMed, http://www.ncbi.nlm.nih.gov) was performed in November 2018 for RCT publications from 1 January 1968 to 31 December 2017. All orthodontic publications, clinical trials (CTs) or RCTs were selected. For each year from 1968 to 2017, the total number of orthodontic publications and total number of CTs and RCTs were computed. Following this, study design, journal publications, authors and countries involved in orthodontic RCTs were noted. The RCTs accounted for 0.1% of all orthodontic publications in the 1970s and 1980s, and, following this, the proportion of RCTs was increased and amounted to 2.7% over the past decade (2008-2017). The majority of RCTs were of single centre design (93.4%) and in 88.3% a parallel-arm design was performed. The United States and United Kingdom endorsed 16.9% and 15.5% of the RCTs, followed by Turkey (11.1%), Brazil (7.0%), Sweden (6.6%), China (5.6%), Italy (5.4%), and Germany (4.1%). Of all RCTs, 74.2% were published in 20 orthodontic journals and 25.8% in 81 non-orthodontic journals. The American Journal of Orthodontics and Dentofacial Orthopedics, Angle Orthodontist, European Journal of Orthodontics and Journal of Orthodontics contributed to 60.2% of all the RCTs. The considerable increase in orthodontic RCTs over the past 50 years implies an increased scientific impact of orthodontic literature