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Demographic characteristics of systematic reviews, meta-analyses, and randomized controlled trials in orthodontic journals with impact factor.

INTRODUCTION
The aim of this study was to explore demographic characteristics of systematic reviews (SRs), meta-analyses (MAs), and randomized controlled trials (RCTs) published in orthodontic journals with an impact factor (IF).


MATERIALS AND METHODS
An electronic search was developed and implemented to identify all the SRs, MAs, and RCTs published in the seven orthodontic journals with an IF. No restrictions were applied regarding language, publication date, or publication status. The initial search generated 1147 articles, which were reviewed by three authors in order to determine if they met the inclusion criteria. Five hundred and fifty-seven articles were included in the final analysis. Type of article, name of journal, year of publication, number of authors, country of origin, and primary affiliation were recorded. Associations between those parameters were tested with the Pearson chi-square test for independence at the 0.05 level of significance.


RESULTS
The majority (72%) of this kind of articles published in the orthodontic literature were RCTs, followed by SRs (20.1%) and MAs (7.9%). Approximately 77.2% of all RCTs, SRs, and MAs were published between 2004 and 2013, and 72.9% came from orthodontic departments. More than 80% of all articles were collaborative efforts between three or more authors. Contributions from Asia, South and Central America significantly increased during last decade, while contributions from North America decreased by almost 30%.


CONCLUSIONS
Most RCTs, MAs, and SRs have been published between 2004 and 2013, indicating a significant improvement of the orthodontic literature during the last decade. Asia, South and Central America have significantly increased their contributions to the high evidence orthodontic literature since 2004.