Publication Metrics of Dental Journals - What is the Role of Self Citations in Determining the Impact Factor of Journals?

Objectives: The objectives of the present study are to examine the publication metrics of dental journals and to delineate the role of self citations in determining the impact factor of journals. Materials and Methods: The Journal Citation Reports database was used. All dental journals that had an impact factor assigned for year 2013 were selected. The outcomes were Impact Factor (IF), Eigenfactor (TM) (EF), article influence score (AIS), and proportion of self-citations to total citations. Independent variables were geographic region of journal and ranking of journal (based on IF). Non-parametric tests were used to examine the associations between outcomes and independent variables. Results: During the year 2013, 82 journals in dentistry had an IF. Mean IF was 1.489 and mean IF without including self-citations was 1.231. Mean EF scores and AIS were .00458 and .5141 respectively. Mean percentage of self cites to total citations for all dental journals was 12.24%. Higher ranking journals were associated with significantly higher EF and AIS. Journals published in USA/Canada or Europe were associated with higher IF and EF compared to those published in other regions. There were no differences in percentages of self citations to total citations either across journal rankings or geographic region. Conclusions: Top ranking journals tend to have higher IFs due to higher EF and AIS rather than by self-citations. Self-citations increase the impact factors of dental journals by 21%. There was no geographic influence in the percentage of self-citations to total citations thus indicating a healthy dental scientific publishing environment.