Introduction: The purposes of this study were to analyze the types of articles and their authorship characteristics in the 3 orthodontic journals with impact factors--American Journal of Orthodontics and Dentofacial Orthopedics (AJODO), Angle Orthodontist (AO), and European Journal of Orthodontics (EJO)--during 2 intervals of 5 years each (1993-1997 and 1998-2002) and to assess the changes in their contents during these periods.
Methods: The results of 3004 article entries were analyzed with the Pearson chi-square test, and the examination of the variability of the parameters studied among journals and across the 2 time intervals was performed at the 0.05 level of significance.
Results and conclusions: Significant differences were found between the journals with respect to the research component of articles (higher in the EJO) and case reports (higher in the AJODO and the AO). For each journal, differences were also identified between the 2 time intervals, with multi-authored papers and multiple affiliations appearing more frequently in the second interval. The contributions of articles from the United States and Canada to the AJODO and the AO were statistically higher than to the EJO. A similar trend was found for articles from Europe, which comprise more than 70% of the content of the EJO. An increased contribution of articles from East Asia and Oceania was noted in the second time interval, which reached almost 100% of the previous time frame. The potential sources of variation in the studied parameters are discussed.