Evidence-Based Dentistry - How to Use It

It was 1784 when the earliest masked assessment seems to have been performed by a commission of inquiry appointed by Louis XVI to investigate the medical claims of  "animal magnetism" or "mesmerism." The goal of the commission was to assess whether the purported effects of this new healing method were due to any "real" force, or caused by the "illusions of the mind." Among the many tests performed, blindfolded people were told that they were receiving or not receiving magnetism when in fact, at times, the reverse was happening. The people being studied felt the effects of mesmerism only when they were "told" and felt no effects when they were not told, whether or not they were receiving the treatment. They were also given what we would now call placebo or dummy treatments of "mesmerized water" and "mesmerized trees."1  

During the 19th century, other major forms of unconventional healing were thought to be the way to treat a patient. Homeopathy claimed that whatever symptom-complex a substance caused in a healthy person, a disease with a similar symptom configuration could be treated by small amounts of the same substance. Orthodox doctors greeted these claims with scorn, and masked assessment was quickly adopted to adjudicate the dispute.2 

During the 1990s, a process emerged for reviewing literature that relied on systematic approaches. This was an improvement to the earlier theory of "bias," "blind studies," and "placebos." When used appropriately by healthcare providers, all available literature is summarized and assessed, thus enabling determination of the best possible treatment for the patient. Evidenced-based dentistry (EBD) has become very important for the well-being of our patients, as well as our relative professional reputations.

EBD involves preparing a systematic review of relevant, reliable research studies on the treatment being assessed. A thorough search is needed to provide unbiased results.

ADA Definition of EBD
EBD is an approach to oral healthcare that requires the judicious integration of systematic assessments of clinically relevant scientific evidence, relating to the patient's oral and medical condition and history, with the dentist's clinical expertise and the patient's treatment needs and preferences.3 The term "evidence" must not be considered synonymous with "science." All information about a dental/health topic must be considered "evidence"  and must be considered as such. Evidence in a courtroom can be considered strong or weak. This also applies to the information we receive regarding dental healthcare. What is important is the ability to critically appraise and synthesize all relevant studies on a specific topic. Even if all of these analyses have been considered, we still have to avoid the danger of being misled by the "play of chance." This is a problem when the research assessing the effects of treatments has not been conducted on a sufficiently large scale. In these circumstances, it can sometimes be helpful to combine the evidence from separate but similar studies by using a statistical approach. For example, in a comparison of a new treatment with a standard treatment, 5 patients improved with the new treatment and 7 patients improved with the standard treatment. It would be wrong to draw the conclusion that the new treatment was worse than the standard treatment. These results might simply reflect chance. If the comparison were to be repeated, the number of patients who improved might be reversed (7 against 5), or have the same results (6 against 6). However, if 50 patients improved with the new treatment and 70 patients improved with the standard treatment, chance becomes a less likely explanation for the difference, and if 500 patients evidenced improvement with the new treatment and 700 patients evidenced improvement with the standard treatment, it would be clear that the new treatment was indeed worse than the standard treatment (which is true of about half of new treatments). The way to reduce the likelihood of being misled by the play of chance is to take into account the experiences of sufficiently large numbers of patients.

Pauline is a 70-year-old new patient who came for a dental exam today. Upon review of her health history, you note that she has slight hypertension and is taking blood pressure medication. She is also taking the antidepressant Paxil. Upon visual examination, you note that she suffers from dry mouth (xerostomia). When questioning the patient about any other symptoms, she indicates a difficulty in swallowing occasionally. You are aware that Lasix is a diuretic and Paxil is a selective serotonin reuptake inhibitor. Both can cause dry mouth. Should we call her physician to discuss alternate medications and a daily fluoride treatment?

Figure 1. Steps to take when generating evidence into actual therapy.

Steps to Take
Exactly what steps can be taken to provide the best appropriate treatment for the patient mentioned above? We need information, but our textbooks are probably out of date. Possibly our journal is disorganized. Consequently, our knowledge, performance, and patient care are probably far from optimal. We gain information through continuing education courses and journals we read. Even though we earn our mandatory CEUs, we might be suffering from "information overload." Possibly only a fraction of the information we have received can be directly applied to our patients. Our practice is busier now than it was 10 years ago. In addition, we have the pressures of insurance companies and reimbursement, which take up our time (Figure 1).

Our first instinct is to go to the library or research our textbooks. In this age of the Internet, we have helpful resources available at our fingertips. Among these are medline.com, medscape.com, and cochranelibrary.com. When in these Web sites, you can query clinical articles or "related articles." Although dental and medical information can be found on the Internet, beware of the quality, reliability, and accuracy of the specific article. MEDLINE, because of its breadth, depth, and continuous maintenance by the US National Library of Medicine (NLM), is the best source of evidence for healthcare. The University of Southern California has an Evidence-Based Web Tutorial at usc.edu/hsc/nml/lis/tutorials.

How Do We Find the Information?

• Internet links offer opportunities to find EBM/ dentistry.
• We learn about this via relevant words or phrases found on the Internet.
• Locate evidence-based policies provided by other colleagues.
• Look for journals that critically appraise primary studies.
• Systematic reviews can be found online by going to (1) the Cochrane Collaboration at cochranelibrary.com and (2) the NLM at nlm. nih.gov. The NLM offers free Internet access through NLM Gateway.4 It is targeted to Internet users who are unfamiliar with the vast contents of the NLM and how to access them. It permits simultaneous, seamless searching in multiple retrieval systems at the NLM. The NLM resources allow users to perform thorough searches that formerly required the expertise of highly trained individuals. The latter statement is not in any way intended to downplay the invaluable role of medical librarians, the real information experts. Indeed, for many scientific endeavors, such as systematic reviews, the expertise of a librarian should be sought.

What Do These Submissions Provide?
• A clear statement of purpose and scope.
• A comprehensive search and retrieval of the relevant research.
• An explicit criteria search.
• Reproducible results because of relevance, selection, and methodological rigor of the primary research.
• Acceptance of proven, evidence-based practice protocols developed by our colleagues (Figure 1).

Journals Online

Online Journals offer a central resource for the most cutting-edge and relevant issues concerning the evidence-based approach in dentistry today. 

These Web sites can give general dental practitioners help online to help them keep abreast of the best available evidence on the latest developments in various aspects of clinical dentistry. In addition, it is an invaluable tool for the specialist practitioners needing to maintain an awareness of new approaches outside their branch of dentistry. The following Web sites offer free abstracts and some have journals which you can buy for a small fee.

sciencedirect.com: the world's best resource for research journals, abstract databases, and reference works.
nature.com: The British Dental Journal is a place to go for issues concerning EBD today.
us.elsevierhealth.com:Information on Periodical Resources along with abstracts.
thejcdp.com: Journal of Contemporary Dental Practice. 

The journal leads dental professionals to new thinking for the 21st century with content that is sound in principle and science. Journal content will foster prevention intervention strategies for disease control.


Figure 2. Understanding the literature pyramid.


The base of the pyramid is where information starts with an idea or laboratory research (Figure 2). As ideas turn into drugs and diagnostic tools, they are tested in laboratories models, in animals, and finally in humans. The human testing may begin with volunteers and go through several phases of clinical trials before the drug or diagnostic tool can be authorized for use within the general population. Randomized controlled trials are then done to test further the effectiveness and efficacy of a drug or therapy. As you move up the pyramid, the amount of available literature decreases, but increases in its relevance to the clinical setting. 

Meta-Analysis takes the systematic review a step further by using statistical techniques to combine the results of several studies as if they were one large study. 

Systematic Reviews usually focus on a clinical topic and answer a specific question. Extensive literature searches are conducted to identify studies with sound methodology. The studies are reviewed, assessed, and summarized according to the predetermined criteria of the review question. 

Randomized Controlled Trials are carefully planned projects that study the effect of a therapy or test on real patients. They include methodologies that reduce the potential for bias and that allow for comparison between intervention groups and control groups (no intervention). Evidence for questions of diagnosis is found in prospective trials that compare tests with a reference or "gold standard" test. 

Cohort Studies take a large population and follow patients who have a specific condition or receive a particular treatment over time and compare them with another group that is similar but has not been affected by the condition being studied. Cohort studies are not as reliable as randomized controlled studies, because the two groups may differ in ways other than in the variable under study. 

Case Control Studies are studies in which patients who already have a specific condition are compared with people who do not. These types of studies are often less reliable than randomized controlled trials and cohort studies, because showing a statistical relationship does not mean that one factor necessarily causes the other. A Case Series consists of collections of reports on the treatment of individual patients. 

A case report is a report on a single patient. Because they are reports of cases and use no control groups with which to compare outcomes, they have no statistical validity. In addition, Practice Guidelines are systematically developed statements to help both the practitioner and patient make decisions about appropriate healthcare for specific clinical circumstances. Guidelines review and evaluate the evidence and then make explicit recommendations for practice. 

The pyramid serves as a guideline to the hierarchy of evidence available. You may not always find the best level of evidence to answer your question. In the absence of the best evidence, you then need to consider moving down the pyramid to other types of studies. 

The type of question is important because this leads you to the correct research (Figure 3).

Five questions we must ask to provide EBD:

(1) Define a clinically relevant and focused question in the interest of finding the best available evidence to promote the oral health of patients. "Best evidence" is a term that refers to information obtained from randomized controlled clinical trials, nonrandomized controlled clinical trials, cohort studies, case-control studies, crossover studies, cross-sectional studies, case studies, or the consensus opinion of experts in appropriate fields of research or clinical practice. See example below: 

"How will quitting smoking alter the risk of oral cancer for my patient with a 30-pack-a-year smoking history?" (A question of prognosis.); or  "How will implementing this program affect my practice financially?" (A question of economic analysis.)
(2) Systematically conduct searches for all studies and databases that, published or unpublished, may help to answer a clinically relevant question. After selecting, summarizing, and synthesizing all relevant studies that directly answer the focused clinical question, the strength of the available scientific evidence is graded by using predefined criteria, and qualitative or quantitative analyses are conducted. Conclusions on the quality and strength of evidence are made, and gaps in the knowledge base that require further research are identified.
(3) Translate the findings from systematic reviews for use by practitioners.
(4) Assess the healthcare outcomes following the findings of the previously outlined steps. This evaluation is conducted as part of the outcome assessment that healthcare providers integrate into their practices.
(5) Discuss the benefits and risks with the patient. 

The objective of this 5-step process is to help practitioners make the best informed decisions for and with their patients.5

Reading and Evaluating

Through the EBD process, we have identified current information that can answer our clinical question. The next step is to read the articles and evaluate the information. 

Three basic questions need to be answered for every type of study:
• Are the results of the study valid?
• What are the results?
• Will the results help in caring for my patient? 

Evaluating the medical literature is a complex undertaking. Once you have determined that the study methodology is valid, you must examine the results and their applicability to the patient. Clinicians may have additional concerns, such as whether the study represented people similar to their patients, whether the study covered the aspect of the problem that is most important to the patient, or whether the study suggested a clear and useful plan of action.

Figure 3. The type of question that leads to the right research.



(1) Was the assignment of patients to treatment randomized? The assignment of patients to either group (treatment or control) must be done by a random allocation. (2) Were all the patients who entered the trial properly accounted for at its conclusion? The study should begin and end with the same number of patients. 
(3) Was follow-up complete? Good studies will have better than 80% follow-up for their patients. 
(4) Were patients analyzed in the groups to which they were (originally) randomized? Anything that happens after randomization can affect the chances that a patient in a study has an event. Patients who forget or refuse their treatment should not be eliminated from the study analysis. 
(5) Were patients, their clinicians, and study personnel "blind" to treatment? Blinding means that the people involved in the study do not know which treatments are given to which patients. With double blinding, neither the patient nor the clinician knows which treatment is being administered. This eliminates bias and preconceived notions as to how the treatments should be working. 
(6) Were the groups similar at the start of the trial? The treatment and the control group must be similar for all prognostic characteristics except one: whether they received the experimental treatment. This information is usually displayed in tables that outline the baseline characteristics of both groups. 
(7) Aside from the experimental intervention, were the groups treated equally? Both groups must be treated the same except for administration of the experimental treatment.6

Grading of the evidence is very important. The purpose of assigning these levels is to give a better idea of the quality and strength of the study. Just because a study has a low grade does not necessarily mean it is an invalid study. It might be the first study of its kind and might hold significance for your consideration.7

WHAT IS NECESSARY TO PROVIDE EBD? All of the following are needed to provide quality of care for your patients (Figures 3 and 4):
(1) individual clinical expertise;
(2) clinicians who increase their judgment through clinical experience and clinical practice; and
(3) the best external clinical evidence is clinically relevant research not only from the basic sciences of medicine, but especially from patient-centered research, accurately diagnostic and clinical exams, and preventive regimens.8

Figure 4. Evidence-based protocol.



To form treatment protocols that are evidence-based, one must have an evidence source that is easily accessible, reliable, and consistent, and one must promise consistency and optimal care. 

The ADA recognizes that treatment recommendations should be determined for each patient by his or her dentist and that patient preferences should be considered in all decisions. Dentist experience and other circumstances, such as patients' characteristics, should also be considered in treatment planning. EBD does not provide a "cookbook" that dentists must follow, nor does it establish a standard of care. The EBD process must not be used to interfere in the dentist/patient relationship, nor is it to be used solely as a cost-containment tool by third-party payers.3 

In brief, to help ensure that healthcare does more good than harm, we need fair research guidelines to distinguish treatments that are useless or harmful from those that are useful. Neither a healthcare professional nor his/her patient can make an informed decision regarding appropriate treatment without considering the relevant data, and thus its alternative (Figure 4).

We have come a long way in the past 200 years. Two hundred years ago, we determined treatment by blindfolding and mesmerism. Today we have a systematic approach using EBD. This is an improvement over the earlier theory of "bias," "blind studies," and "placebos." Through technology and the Internet, we are able to more easily research the most current information for the best treatment on an individualized basis for each patient.


1. Kaptchuk T. Control of observer biases: masking (blinding) and placebos. NY State J.1998:46:1718-1727. 
2. Dingwall EJ. Abnormal Hypnotic Phenomena: A Survey of Nineteenth-Century Cases. 4 vols. London, England: Churchill; 1967-1968. 
3. ADA. Policy on evidence-based dentistry. www.ada.org. Accessed on: November 29, 2003. 
4. Bordley DR. Evidence-based medicine: a powerful educational tool for clerkship education. Am J Med. 1997;102:427-432. 
5. Ball C, Sackett D, Phillips B, et al. Statement of primary goals/levels of evidence. J Evidence-based Dent. 2002;2:64.
6. Richardson WS, Wilson MC, Nishikawa J, et al. The well-built clinical question: a key to evidence-based decisions. Am College Physicians J. 1995;123:A12-A13. 7. Jokstad A. Evidence-based Dentistry and Bibliometry/Table of Contents [Lecture]. Department of Prosthetics and Oral Function. Dental Faculty, University of Oslo. Oslo, Norway, July 1999. 
8. Straus SE, Sackett DL. Getting research findings into practice: using research findings in clinical practice. Br Med J. 1998;317:339-342. 

Ms. Seidel-Bittke is a dental management consultant, author, international speaker, and CEO of Dental Practice Solutions, a leading-edge speaking and dental consulting firm. She places high priority on helping her clients attain their goals through practical methods that work for everyone. She has extensive experience as a dental hygiene clinician, having worked with numerous private practices where she stressed comprehensive periodontal care for all patients. In addition, Ms. Seidel-Bittke is a former clinical assistant professor at the University of Southern California. She has been an active member of the American Dental Hygienists' Association for the last 20 years and is also a recognized member of the National Speakers Association. Her mission is to assist dental professionals with updating their office protocols, improving instrumentation skills, increasing dental team compatibility, upgrading the standard of care, and effectively addressing in-office time management issues. Her confident and friendly approach is well received by dental teams throughout the country. Ms. Seidel-Bittke can be reached at (949) 215-9072, at This e-mail address is being protected from spambots. You need JavaScript enabled to view it , or visit dentalpracticesolutions.com.

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