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1 Center for Dental Informatics, School of Dental Medicine, University of Pittsburgh, 3501 Terrace Street, Pittsburgh, PA 15261;
2 Division of Pediatric and Developmental Dental Sciences, School of Dental Medicine, University of Pittsburgh;
3 Health Sciences Library System, Falk Library of the Health Sciences, University of Pittsburgh;
Correspondence: * corresponding author, titus{at}pitt.edu
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Abstract |
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KEY WORDS: Dental informatics • information retrieval • literature • MEDLINE
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Introduction |
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While the dental informatics literature is still sparse, the literature is an important resource in describing new scientific fields (Bush, 1996; Morris and McCain, 1998). The analysis of papers and articles can be used to define a field, determine its boundaries to other fields, describe the research problems and topics it addresses, and identify trends. An analysis of the biomedical informatics journal literature in 1998 (Morris and McCain, 1998) used intercitation and co-citation analyses to elucidate the field’s structure. In examining citation patterns among 20 biomedical informatics journals, the authors found that the major focus areas in the field included biomedical engineering, biomedical computing, decision support, and education. The authors noted that none of the journals in specific application areas of informatics, such as nursing and dentistry, ranked high enough in the exploratory analyses to be included in the final analysis. This reflects the fact that even until today no dedicated dental informatics journal (with the possible exception of the Journal of Computerized Dentistry, published by Quintessence Publishing, Inc.) exists.
However, the number of dental informatics papers in journals such as the Journal of the American Medical Informatics Association, the Journal of the American Dental Association, and the Journal of Dental Education is rising. We therefore concentrated on the single paper as the unit of analysis in our study. The scattering of the dental informatics literature among many journals resembles the dispersion of the biomaterials literature found in 1996 (Bush, 1996). Biomaterials scientists listed 65 journals that were of interest to their work. As a consequence, the retrieval of relevant papers was seen as a major obstacle in this emerging discipline.
We anticipated similar retrieval problems in the dental informatics literature. Since "dental informatics" first appeared in the MEDLINE-indexed literature only in 1986, it is intuitive that most work in this field is not yet labeled as such. As of this writing, searching for "dental informatics" in MEDLINE using the PubMed interface (National Library of Medicine, 1998) yielded about 200 citations. The same query for "medical informatics" retrieved over 295,000 citations. To the observer even only marginally familiar with both fields, the number of dental informatics citations appears artificially low. The retrieval problem for this literature is therefore evident at first glance.
The objective of this study was to perform an initial, general analysis of the dental informatics literature. Our first interest was how best to retrieve it. Second, we wanted to determine its size, the number of authors, its distribution across journals, its growth rate, and its general content as expressed by Medical Subject Headings (MeSH). We performed the same analyses with the information technology (IT) literature in dentistry, to gain an understanding about the relative characteristics of each of those literatures.
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Methods |
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A second consideration is the relationship between dental informatics and its parent discipline, biomedical informatics (Schleyer, 2003). Dental informatics, just as other applied informatics fields, contributes to the basic theory and concepts underlying all of biomedical informatics. Generalizable methods become dissociated from the particular domain problem that may have given rise to their development, and thus become part of the methodological foundation of biomedical informatics. In examining a particular research paper, it might be difficult to label its subject "dental informatics" if it describes a universally applicable method. We therefore expected fundamental methods papers in our result set only if they referenced the dental research problem that resulted in the development of the new method.
Our initial search strategy for the dental informatics literature was comprised of three concepts: dentistry, computers, and research. This search strategy was intentionally broad, because high sensitivity (i.e., not missing any potentially relevant citations) was very important. For dentistry, we included 48 high-level Medical Subject Headings (MeSH) terms, such as "stomatognathic system", "dental records", "dental research", and "education, dental". All high-level headings were exploded in the search. The concept "computers" included eight search terms, such as "technology", "medical informatics", "dental informatics", and "computers" truncated to capture all citations containing words that began with "comput". The concept of "research" presented a special problem, since it is a meta-concept that is not normally applied to citations in MEDLINE (Bartling et al., 2003). We attempted to cover this subset by searching for research-related terms (such as "statistics", "results", "study", and "methods") in titles and abstracts. We excluded the publication types "comment", "editorial", and "letter" from the search results. We also eliminated articles without abstracts, which biased the results toward more recent publications. Since abstracts were crucial to determining the content of publications, we accepted this limitation. We placed no restrictions on the language in which articles had been published.
We ran this initial search strategy on the MEDLINE database via Ovid from 1966 to April, 2003. We then randomly sampled 800 papers from this initial result set, and two authors (TKS and PC) classified them jointly for content (see Fig.
). The content classifications were (1) non-dental, (2) dental but neither dental informatics nor IT-related, (3) dental informatics, and (4) IT in dentistry. We discussed disagreements and reconciled them directly. The purpose of this initial review was to determine any difficulties or problems in classifying papers, and to estimate the percentage of relevant citations in the initial search results.
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After eliminating all irrelevant terms, we re-ran the refined MEDLINE search, and examined the result set again regarding the proportion of relevant articles. (The final MEDLINE search strategy and result set for dental informatics and dental IT papers are available online at http://di.dental.pitt.edu/DIlitreview/.).
At this point, it was impossible to refine the search strategy further without expending significant effort, and we decided to filter the final set using a small group of expert raters (dental informatics faculty and post-graduate students). Each rater was assigned several hundred citations, which they classified independently.
We then analyzed the resultant set of dental informatics papers by computing MeSH term frequencies, and calculating journal counts and author frequencies. We also plotted the yearly publication output in both the informatics and IT categories. These analyses provided an initial summary view of both the dental informatics and dental IT literatures.
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Results |
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. The initial, broad search strategy (Fig., Step 1) incorporating the concepts "dentistry", "computers", and "research" resulted in the retrieval of 10,477 citations. The random sample of 800 citations extracted from this set ((Fig., Step 2) consisted of 37% non-dental articles (297 citations), 56% dental, but not informatics-or IT-related, articles (448 citations), and 7% informatics- or IT-related articles (55 citations). The analysis of MeSH term frequencies in the set of non-dental articles determined that 72 terms occurred more than ten times, 25 terms eight or nine times, 60 terms six or seven times, 153 terms four or five times, and 147 terms three times. From this total of 457 terms, we were able to eliminate 305 inappropriate terms. Excluding these terms from the search reduced the size of the result set by 6548 citations. Examples of eliminated terms included "Sleep Apnea Syndromes", "Orbit", "Hip Prosthesis", and "Pharyngitis". The final raw set consisted of 3929 citations.
After the elimination of 57 duplicates (Fig., Step 3), the final set contained 3872 citations. A group of two dental informatics faculty and three post-graduate students in dental informatics manually classified the citations in this set. Due to resource constraints, each citation was reviewed by only a single individual. The final set contained 12% non-dental articles (463 citations), 59% dental, but not informatics-or IT-related, articles (2278 citations), 16% informatics-related articles (620 citations), and 13% IT-related articles (511 citations). Compared with our initial result set, our filtering approach reduced the proportion of non-dental articles by more than two-thirds, left the proportion of dental articles about the same, and increased the proportion of informatics- and IT-related citations by a factor greater than four.
We then analyzed the set of 620 informatics-related citations and 511 IT-related citations as described above. As a consequence of retrieving only citations with abstracts, the earliest citation in both sets was from 1975. While research on computer applications in dentistry had been published prior to 1975, it could not be retrieved with our methods. The informatics-related citations appeared in 176 journals, and the IT-related citations in 206 journals. Journals with the most informatics-related citations (see Table 1; limited to journals with seven or more citations for dental informatics) included Dento-Maxillo-Facial Radiology (n = 56), Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, & Endodontics (n = 69), and the Journal of Dental Education (n = 25). Journals with the most IT-related citations (limited to journals with seven or more citations) included Dento-Maxillo-Facial Radiology (n = 24), Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, & Endodontics (n = 21), and the Journal of Prosthetic Dentistry (n = 14).
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shows the yearly publication output in the categories of interest. Currently, approximately 50 papers are published annually in each of the categories dental informatics and IT. Between 1975 and 2002, the historical yearly growth rate for informatics-related papers has been approximately 19%, while it was 20% for IT-related papers. However, mainly due to the small numbers of publications, earlier years show a much higher variability in the growth rate than later years. For the last ten years, the yearly growth rate for dental informatics was approximately 10%, and for IT 11%.
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The major MeSH terms according to which dental informatics papers are indexed fall into roughly four categories (see Table 3). "Imaging and Image Processing" is a major topic in 129 (or 72%) of the papers. Primarily, these papers are concerned with digital dental radiography. However, other imaging modalities—such as computed tomography, magnetic resonance imaging, and three-dimensional imaging—are also represented. With 22 occurrences (or 12%), "Computer-aided Diagnosis and Therapy" is the second most frequently treated topic. "Computer-aided Instruction", with eight occurrences (or 4%), is the third most frequent category. Twenty-one terms (or 12%) were too generic to be included in any other category.
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Discussion |
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Dental informatics papers are spread across a large number of journals, and this makes it difficult to define a cohesive literature. Some journals, such as the Journal of the American Dental Association, have established a section for informatics, which may serve as a better focal point for informatics-related papers. The number of very active authors, both currently and historically, is quite low. The number of authors with fewer than three total publications is very high, and may reflect the broad but relatively superficial interest in this discipline. At this point, it seems premature to assume that the dental informatics community could support one or more journals of its own. Not enough trained dental informaticians exist to produce a steady stream of research papers of high quality. In addition, it appears more useful to introduce dental informatics research to a mainstream audience in dentistry than to provide an additional communication forum for a very small group of individuals.
The predominant area of research in dental informatics is imaging and image processing. This is intuitive, inasmuch as imaging, in its various forms, plays a significant role in clinical dental care. Among the major subject areas, computer-aided diagnosis and therapy and computer-aided instruction also receive significant attention in the literature. Interestingly, the top-level classification of research topics in dental informatics closely resembles that found in biomedical informatics (Morris and McCain, 1998), despite the fact that those classifications were determined by very different methods. A more fine-grained analysis of research topics in dental informatics will be the subject of a future study.
This study has several important limitations. The total number of dental informatics citations worldwide since 1975 is most likely higher than 620. Several circumstances are responsible for this limitation. In our literature search, we focused on the MEDLINE database only. Other databases, such as the Science Citation Index, and hand-searching non-indexed journals would have provided additional citations. The number of publications on IT in dentistry is probably underestimated to a greater extent than the number of publications in dental informatics. The reason for this circumstance is that our search focused on research publications, and thus eliminated many publications on IT that did not match our search criteria. However, since informatics was our primary focus, this limitation is acceptable.
It is uncertain whether research in countries other than the US is represented to the same degree as research published in the US. Aside from the US, Europe is a major contributor to the informatics literature. Another limitation was the fact that we excluded citations without abstracts. This decision eliminated from our result set the early work in dental informatics dating back to the 1960s and early 1970s. Finally, we do not have a true measure for the recall (or sensitivity) of our search strategy. The MEDLINE database may contain additional relevant dental informatics citations that we missed by our choice of search terms. We attempted to counteract this possible limitation by formulating our initial search strategy as broadly as possible, and then eliminating only irrelevant citations from the results.
As a follow-up to this study, we plan to perform a more detailed review and classification of the dental informatics literature. For instance, one area of interest is where dental informatics has made specific contributions to the theoretical biomedical informatics literature. Another goal of this subsequent study would be to examine in more detail the research that has been performed in dental informatics, its results, and the implications for future research.
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Acknowledgments |
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Footnotes |
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References |
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Bush RB (1996). Biomaterials: an introduction for librarians. Sci Technol Libr 15(4):3–28.
Friedman CP (1995). Where’s the science in medical informatics? J Am Med Inform Assoc 2:65–67.
Morris TA, McCain KW (1998). The structure of medical informatics journal literature. J Am Med Inform Assoc 5:448–466.
National Library of Medicine (1998). Welcome to PubMed. [Online]. Available: http://www.ncbi.nlm.nih.gov/PubMed/. Accessed 3/26/2004.
Schleyer TK (2003). Dental informatics: an emerging biomedical informatics discipline. J Dent Educ 67:1193–1200 and Adv Dent Res 14:4–8.
Schleyer T, Spallek H (2001). Dental informatics. A cornerstone of dental practice. J Am Dent Assoc 132:605–613.
Yang S, Needleman H, Niederman R (2001). A bibliometric analysis of the pediatric dental literature in MEDLINE. Pediatr Dent 23:415–418.[Medline]
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