11 Reading the Dental Literature
The literature is the generic name given to the body of writing in books, journals, reports, and other sources that makes up the sum of knowledge in a branch of science. In the case of dentistry we refer to the dental literature. However, the literature is more than just our compendium of knowledge and our scientific base; it is our very identity. It defines who we are and what we do; it charts the progress of dentistry to its present status and provides guidelines for future directions.
Technologic and social developments, in dentistry as elsewhere, are proceeding at a speed that can be both bewildering and overwhelming. Although dental and dental hygiene graduates learn enough in professional school to begin practice, “keeping up” is absolutely essential for professional growth. Attendance at continuing education courses is one way to do so (such attendance is required in most states), but the literature is the primary source of new knowledge. Therefore it follows that dentists and hygienists must keep familiar with those sections of the literature that most concern them if they are to function properly. To do this, they need to be able to locate the literature they need and read it critically; they need to distinguish front-line from mediocre journals and be aware of how to distinguish good from poor research. Acquiring these skills requires some time and practice, but confidence with them will pay off in helping practitioners use their time efficiently while they grow professionally. Professional training, unfortunately, does not usually include critical reading. The usual progression begins with accepting the veracity of reports unquestioningly and without conscious thought, because “if it weren’t true, it wouldn’t be printed.” After being misled a few times, readers can become increasingly skeptical. In the extreme, they can move full circle from believing everything they read to believing nothing. The ideal course is between the two extremes, somewhere between blind acceptance and blanket mistrust.
This is the first of two chapters on how to efficiently locate and interpret information that is needed for effective clinical practice. This chapter deals with assessing the quality of an individual report in the literature, whereas Chapter 12 is devoted to evidence-based dentistry and assessment of a body of literature to determine best clinical practices.
Textbooks are the most familiar source of information for students. Although good books may be the first source to be consulted on a subject, books can soon become dated. The copy a student buys from the bookshop may be new, but if it was published 10 years ago then at least parts of it risk being obsolete. That proviso accepted, the best textbooks present the state of the science, at least at the date of publication, as well as a sound foundation on which to build further information.
Journals are the basic source of current information in any science-based field, dentistry included. The number of journals in dentistry, as in most other disciplines, has proliferated in recent years. It is virtually impossible for anyone to keep up with all journals, so selectivity is needed. There are good journals and not-so-good ones, and there are some clues to picking which is which. The most basic is that good journals are all peer reviewed.
Peer review means that manuscripts, when first received by the journal editor, are sent out to be reviewed by several experts in the subject area of the manuscript. Usually two reviewers are selected, sometimes more, and the identity of the reviewers is concealed from the authors to promote candid reviews. Some journals, though not all, also mask the identity of the authors from the reviewers in an effort to remove any bias from the reviewers’ judgment. The reviewers’ task is to assess the manuscript critically for the quality of its science, its logic, its manner of presentation, and any other feature that might reflect on its value in the literature. Poor-quality manuscripts can be rejected outright at this stage or returned to the authors for revision if the papers are basically sound but have room for improvement. Most articles published in journals have been returned to the authors for revisions at least once prior to acceptance. Many prestigious journals, such as the New England Journal of Medicine, reject far more manuscripts than they publish; their reviewing standards are extremely rigorous. The top dental journals publish well under half of the manuscripts they receive.
Peer review is a system that has evolved through the years, and there is no question that it has served to greatly elevate the standards of published material. However, it does have some limitations. For example, the process can suffer when the reviewers chosen are inappropriate, either because they are not sufficiently expert in the field of study or because their own prejudices get in the way of an objective review. More common are reviewers who simply do not give a manuscript the attention it deserves. An inherent problem is the tendency of the peer-review process to inhibit original research or creativity and to push imaginative thoughts into a safe middle ground. On balance, however, peer review has served to greatly elevate the quality of the literature.
The first step in judging a journal’s quality is to find out whether it is peer reviewed or not. Some provide this information in their instructions to contributors, which journals publish regularly and which can usually be found on the journal’s website. The second thing to find out is the journal’s sponsorship: who puts it out? Here are four broad categories of sponsorship:
A Learned Society Learned societies frequently present the best and most important research papers—their reason for existing, after all, is to promote and disseminate research findings. Some, like the International Association for Dental Research, which publishes the Journal of Dental Research, Critical Reviews in Oral Biology and Medicine, and Advances in Dental Research, promote dental research in all fields; others advance research in specialized or semispecialized areas. Journals published by learned societies are invariably peer reviewed and have a strong emphasis on scientific rigor. These journals are characterized by a straightforward format with a relative absence of advertising, a strong editorial board, and explicit instructions to contributors. On the down side, a relatively small circulation to a specialized group often makes them expensive.
A Professional Organization A professional organization is a dental or dental hygiene association, a specialty society, or any other professional group. The best journals in this category, such as the New England Journal of Medicine, British Medical Journal, and Journal of the American Medical Association, rank among the most prestigious in biomedicine. The majority of journals in this group are peer reviewed. In contrast to the journals published by learned societies, these can show some bias in choice of material: there can be a tendency to publish papers favorable to the organization’s views and not to publish papers with contrary views, regardless of their quality. These journals can carry a fair amount of advertising, which together with wide distribution to the association’s membership keeps the price moderate. In the better journals, advertising material must pass editorial scrutiny for factual content and taste.
A Reputable Scientific Publisher Some journals are produced by publishers of medical and dental texts to fill a need: Community Dentistry and Oral Epidemiology and Journal of Periodontal Research, published by Blackwell Scietific Publishers, are examples. The best journals in this group are rigorously peer reviewed and generally are the equal of those issued by learned societies in terms of quality.
A Commercial Publisher Journals issued by commercial publishers comprise a category often referred to as “throwaways,” and some can be more accurately described as magazines rather than journals. They carry a lot of advertising, which often permits them to be distributed free of charge, and their articles are often written by professional in-house staff. Some do accept contributed papers, but peer review is unusual. The scientific quality of these journals is usually not high, for that is not their function. These journals fill a niche, as long as readers recognize them for what they are.
The third step in quality determination is to look for a listing of an editorial board, advisory board, or consultants. These terms can be used loosely and interchangeably, and the functions of these groups can vary widely, from taking an active role in journal policies to being little more than window dressing. The presence of such a list, however, suggests that the journal is at least trying to keep up standards.
As the fourth step, a reader should be able to judge the nature of the papers from a quick perusal: research reports, case reports, opinion pieces, reviews, political commentary. First and most important, the reader should be able to tell which is which. Looking over the editorials, in those journals that carry them, can give a feeling for any particular political stance the journal may take.
The fifth step can be to scan the advertising for the products and services presented, and the advertising style. Better-quality journals either have no advertising or a reasonably restrained advertising style. Look for some statement of advertising policy, such as is found in the advertising index of each issue of the Journal of the American Dental Association.
Finally, the production standards should be checked. Typographical errors, lack of consistency, and inadequate citations in references can make a reader wonder what else is wrong that is less readily apparent.
A professional’s ability to understand scientific reports in the literature demands some grasp of research design. Although the principles of research apply to all kinds of scientific inquiry, the details described in the following paragraphs relate specifically to epidemiologic studies and to clinical trials.