The Evolution of Dental Journals from 2003 to 2012: A Bibliometric Analysis

March The Evolution of Dental Journals from 2003 to 2012: A Bibliometric Analysis Yasas Shri Nalaka Jayaratne 0 1 Roger Arthur Zwahlen 0 1 0 1 Division of Orthodontics, Department of Craniofacial Sciences, University of Connecticut School of Dental Medicine , 263 Farmington Avenue, Farmington, Connecticut 06030 , United States of America, 2 Discipline of Oral & Maxillofacial Surgery, Faculty of Dentistry, The University of Hong Kong , Pokfulam , Hong Kong Special Administrative Region 1 Academic Editor: Vince Grolmusz, Mathematical Institute , HUNGARY Bibliometrics are a set of methods, which can be used to analyze academic literature quantitatively and its changes over time. The objectives of this study were 1) to evaluate trends related to academic performance of dental journals from 2003 to 2012 using bibliometric indices, and 2) monitor the changes of the five dental journals with the highest and lowest impact factor (IF) published in 2003. Data for the subject category "Dentistry, Oral Surgery & Medicine" was retrieved from the Journal Citation Reports (JCR) published from 2003 to 2012. Linear regressions analysis was used to determine statistical trends over the years with each bibliometric indicator as the dependent variable and the JCR year as the predictor variable. Statistically significant rise in the total number of dental journals, the number of all articles with the steepest rise observed for research articles, the number of citations and the aggregate IF was observed from 2003 to 2012. The analysis of the five top and five bottomtire dental journals revealed a rise in IF however, with a wide variation in relation to the magnitude of this rise. Although the IF of the top five journals remained relatively constant, the percentile ranks of the four lowest ranking journals in 2003 increased significantly with the sharpest rise being noted for the British Journal of Oral & Maxillofacial Surgery. This study revealed significant growth of dental literature in absolute terms, as well as upward trends for most of the citation-based bibliometric indices from 2003 to 2012. - Competing Interests: The authors have declared that no competing interests exist. Journals play a vital role in academia by disseminating scholarly and technical work, evaluating and peer-review of research, archiving of such work and serving as basis for scholarly credits [1]. Peer-reviewed publications have been designated as the primary mode of communication and record for scientific research [2]. Olk and Griffith in 2004 argued that journals still represent the primary source of knowledge in a given field. They stated that scholars push the boundaries of their field but journals are needed to advance the main body of knowledge [3]. The worlds first dental journal, The American Journal of Dental Science, started its publication in 1839 [4]. Since then the journals in the field of dentistry have been acting as a source of knowledge and mode of communication within the dental community and other disciplines. Many changes can occur in the lifetime of a single academic journal or a in a group of journals. Thus, reliable techniques to document and analyze such changes are needed. Bibliometrics are a set of methods to analyze academic literature quantitatively [5]. Basically this term means the application of quantitative analysis and statistics to publications such as journal articles and their accompanying citation counts[6]. Such analyses can be used to evaluate the impact of publications at different echelons including the level of a single author, a group of researchers, a specific paper, a journal, a particular field, or an academic institution. The impact factor (IF) published by Thomson Reuters annual Journal Citation Reports (JCR) remains to be a popular bibliometric index. The journal IF indicates the average number of times articles published two years ago were cited in the JCR year. It is calculated by dividing the total number of citations to a particular journal in the JCR year by the number of articles published in that journal in the past two years [7]. The JCR contains a number of bibliometric data and indices other than the IF, which can reveal important information about the performance of each journal. Moreover, it is possible to retrieve from JCR, aggregate data for all journals belonging to a certain subject category. Such category data enables the evaluation of bibliometric trends within a particular specialty as a whole. The progress of dental journals has not been studied in the past. With bibliometric information, it is possible to gauge the growth and other characteristic changes in the field. Consequently, insights can be gained on how dentistrys collective body of knowledge is evolving over time. Therefore, this study was designated 1) to evaluate trends related to academic performance of dental journals from 2003 to 2012 using bibliometric indices, and 2) to monitor changes of the five dental journals with the highest and lowest IFs published in 2003 and remaining in circulation up to 2012. The science edition of the Journal Citation Reports (JCR) available on the ISI Web of Knowledge database was used for this study. Data available for the subject category grouped in the JCR as Dentistry, Oral Surgery & Medicine was searched from 2003 to 2012. Year 2003 was used as the starting point because subject category data were introduced from this year onwards, while 2012 was used as the endpoint, as the latest available JCR was of this year. The raw data is available from the Journal Citation Reports published by Thomson Reuters. However, users need to have a subscription to access this database. Several bibliometric indicators were collected from the subject category page for Dentistry, Oral Surgery & Medicine for each JCR year. Descriptions of these indicators, as presented by its publisher [7] are shown below in italics: 1. Number of journals 2. Their publication frequency (annual, semiannual, quarterly, bimonthly, monthly) 3. Total citesthe total number of citations to journals in the subject category in the JCR year 4. Median impact factorthe median value of all journal impact factors in the subject category 5. Aggregate impact factorcalculated the same way as the Impact Factor for a journal, but it takes into account the number of citations to all journals in the category and the number of articles from all journals in the category 6. Aggregate immediacy indexThe Immediacy Index is the average number of times an article is cited in the year it is published. The Immediacy Index is calculated by dividing the number of citations to articles published in a given year by the number of articles published in that year. The aggregate Immediacy Index indicates how quickly articles in a subject category are cited. 7. Aggregate cited half-lifethe median age of the articles that were cited in the JCR year. The aggregate cited half-life is an indication of the t (...truncated)