12 Evidence-Based Dentistry
What do you do when a periodontal patient says, “I read in a magazine that gum disease can cause a heart attack but that there is a drug available to prevent this. Should I be taking this drug?” Chances are that you don’t know how to respond. You may have studied the relationship between periodontitis and cardiovascular disease (see Chapters 21 and 29), but you have never heard of the drug the patient describes. Your first instinct is probably to dismiss the whole thing, but you have a nagging feeling that perhaps there is something in it. So what do you do? That is the theme of this chapter: to look at the emerging field of evidence-based dentistry (EBD) and to see how you can use it in practice. This chapter describes what EBD is, why increased attention is being given to EBD, how this emphasis will affect oral health professionals in the future, and what responsibilities come with adherence to evidence-based practice.
EBD is sometimes described as doing the right thing, for the right patient, at the right time. This definition is succinct and hard to dispute, but it still leaves the practitioner with little concrete direction in the day-to-day, patient-by-patient decisions that must be made in practice. What, in fact, is the right thing to do in each situation that presents itself, who is the right patient to treat with which procedure, and when is the time right? These are complex questions and usually do not have clear-cut answers.
The conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients. The practice of evidence-based medicine means integrating individual clinical expertise with the best available external clinical evidence from systematic research.21
There are three essential components of EBM: the scientific base for any treatment decision a practitioner makes, the clinical expertise of the practitioner, and the patient’s values. Dentistry has come to this field later than medicine and has for the most part adopted the same language and conventions. So the definition just given for EBM is applied to EBD, as are the three components, although this more detailed definition also requires interpretation before the clinician can be confident about how it applies in the day-to-day clinical practice of dentistry. Both EBM and EBD relate to patient care (rather than research or administration) and are invoked when the practitioner is seeking to make the best treatment decision for a particular patient.
But hasn’t dentistry always based treatment decisions on scientific evidence? Well, yes and no, as we’ll discuss further. The landmark Gies report of 1926 noted “the growth of quackery” during the nineteenth century,9 and even the 1995 Institute of Medicine report on the future of dental education recommended greater development of the scientific base in dental practice.11 The modern evidence-based approach in medicine, which got underway during the 1970s, is now well established, one could almost say institutionalized. The years between the 1970s and the present day saw an evolution of the methods for the systematic collection of information in EBM and its application to clinical practice, so that today, as we develop EBD, we can benefit from the experience of our medical colleagues. What is now emerging in dentistry is the formal recognition that clinical decision making requires the application of the rigorous rules of evidence. One sign of this increased attention is the establishment of two journals on the topic: Evidence-Based Dentistry first appeared as a supplement to the British Dental Journal in 1998 and became a stand-alone journal in 2000. The Journal of Evidence-Based Dental Practice began publication in the United States in 2001.
The phrase the art and science of dentistry means that when we care for our patients we combine our clinical acumen, experience, and human sensitivity with procedures that are based on the most up-to-date science. Essentially, the “art” of dentistry is the acceptance of the individuality of each patient. We recognize that a treatment we think appropriate for one person will not necessarily be appropriate for another with the same condition. We use the art side of our practice to assess the patient’s interest in his or her oral health when formulating a treatment plan. We also factor into the treatment plan the patient’s age, existing state of oral and general health, and ability and willingness to pay for treatment. The art of dentistry also includes the clinician’s individual ability in using certain materials or techniques. Sometimes a clinician will have a special knack for working with a material or procedure and so can make a given treatment perform better than the average clinician would.
This art aspect of clinical dentistry should remain. It is only out of place when the opinions, beliefs, and attitudes of the dentist, no matter how well intentioned, are allowed to override facts that are clearly demonstrated through science. There should be a mix of art and science in each treatment plan, but the procedures that we consider as treatment options should, as far as possible, be justified by science. There will be occasions in which a scientific base for a treatment option is nonexistent, and in these cases the practitioner has to determine what the best practices are. In such cases it is up to the dental research community to see that resources are directed into these areas to ensure that the necessary scientific base is developed.
It is useful to distinguish between the principles of EBD and the methods that have been proposed for implementing it. Regarding the principles there is little dispute, for no one can argue against using evidence as the basis for care. This philosophical stance, however, is immediately followed by the practical issues of (1) what qualifies as evidence, and (2) how we evaluate that evidence. With EBD, the traditional ad hoc and subjective approach to these issues is replaced by explicit and objective methods to evaluate the available evidence. We recognize that today it is more difficult than ever for clinicians to assess all of the rapidly expanding treatment options before deciding on their value to their patients. Although the methods of EBD are not a panacea for the challenge of increased options, they do provide a framework for a systematic and unbiased approach to evaluating those options. Rather than requiring an ad hoc assessment by each individual clinician to determine the strength of the scientific evidence on each aspect of dental care, EBD uses a systematic process to assemble, evaluate, and summarize the evidence on particular treatment questions.
If the quality of the scientific evidence is to form an important part of our clinical decision making, then how do we judge the quality of that evidence? In Chapter 11, we looked at how to evaluate the quality of an individual paper. In terms of assembling components of the scientific base to support a treatment procedure, EBM and EBD extend that analysis by objectively measuring the quantity and quality of the body of evidence on a subject. The traditional process is by means of the narrative review (see Chapter 11) in which an expert, or experts, assesses the literature on the subject and then reaches conclusions. Again as noted in Chapter 11, the quality of such reviews varies from brilliant to mediocre or even misleading. This range results from differences in the research attention the subject has received, the thoroughness of the literature search, and the ability and objectivity of the reviewer.
An inherent problem in any literature review is the variation in quality of research reports on the subject. As stated in Chapter 11, to be of value any review must be a critical review; that is, the variation in quality of the various research reports must be explicitly recognized. Recognition is a good first step, but the reviewer still has to deal with the issue. This variation in the quality of the literature was a problem facing a Canadian expert panel in the 1970s whose task was to assess the value of the annual physical examination in preventing mortality and morbidity.4 To deal with the range in quality of the papers on the subject, the Canadian group developed a hierarchical scale to give a quality score to each paper the members were reading. This scale is shown in Table 12-1. These quality scores were the basis for the recommendations issued on the use or rejection of the procedure (Table 12-2). This methodologic approach had sufficient appeal to be adopted a few years later by the U.S. Preventive Services Task Force25 and, in slightly modified form, by the Centers for Disease Control and Prevention for a major report on fluoride (see Chapter 26) a few years later.26 This approach does require some summary judgments by the review panel when the research reports on testing of a procedure are of mixed quality. Scaling the quality of a whole body of evidence as a unit still has some application, although the principal method now used for assessing the quality of a body of evidence is the systematic review, which is based on grading each of the individual reports selected and then reaching an overall conclusion.
|I||Evidence obtained from one or more properly conducted randomized clinical trials (i.e., one using concurrent controls, double-blind design, placebo, valid and reliable measurements, and well- controlled study protocols).|
|II-1||Evidence obtained from one or more controlled clinical trials without randomization (i.e., one using systematic subject selection, some type of concurrent controls, valid and reliable measurements, and well-controlled study protocols).|
|II-2||Evidence obtained from one or more well-designed cohort or case-control analytic studies, preferably from more than one center or research group.|
|II-3||Evidence obtained from cross-sectional comparisons involving subjects at different times and places, or studies with historical controls. Dramatic results in uncontrolled experiments (such as the results of the introduction of penicillin treatment in the 1940s) could also be regarded as this type of evidence.|
|III||Opinions of respected authorities, based on clinical experience; descriptive studies or case reports; or reports of expert committees.|
|A||There is good evidence to support the use of the procedure.|
|B||There is fair evidence to support the use of the procedure.|
|C||There is a lack of evidence to enable a specific recommendation to be made; i.e., the subject has not been adequately tested. This grade will also apply to mixed evidence; i.e., some studies support the use of the procedure and some oppose it.|
|D||There is fair evidence to reject the use of the procedure.|
|E||There is good evidence to reject the use of the procedure.|
For most of us, the most convenient way to catch up on a subject is to read reviews of the literature. The traditional format is the narrative review, which often takes the form of a paper given at a conference or symposium, in which the authors assess the information from published reports on a topic and then reach a conclusion based on the weight of evidence. Narrative reviews have been around for ages and generally have served a valuable purpose, but they can have limitations because of their subjective nature.18 The first problem with any type of review is that not all research gets published. A/>