Evidence-Based Dentistry Makes Practice More Predictable
Margaret I. Scarlett
How dentists evaluate established practices and how they incorporate new ones are critical elements in the ever-evolving practice of oral health care. Unfortunately, the sources available to inform these decisions are almost as varied as the choices themselves. Symposia and platform presentations at national and regional dental conferences, articles in journals or newsletters, presentations by sales representatives, practice-management consultants, and even other dental colleagues all compete for attention as information tools, often leading to confusion and a lack of unbiased consensus regarding the clinical value of a technique or product.
But that may be changing thanks to the vogue of evidence-based dentistry. Evidence-based dentistry is a set of recommendations calculated on the strength of a careful scientific review of the literature on a topic that can be used by dentists to assist in clinical decision making. These scientific reviews are beginning to lead the way to helping us understand what has worked and what we might expect to work for our patients. Think of them as another practice-management tool for practitioners who lack the time, experience, or expertise to review evidence in hundreds of scientific articles.
THE BURDEN OF PROOF
Evidence-based dentistry is an application of a process that emerged in other health fields. In 1989, the Guide to Clinical Preventive Services was published by the first US Preventive Services Task Force.1 This panel, formed under the umbrella of the Department of Health and Human Services and composed of academicians, government officials, and clinicians, evaluated the effectiveness of existing clinical preventive services, new scientific evidence, and new technologies that merited consideration. The guide used an algorithm of decision rules for evaluating the science, with the highest recommendation given for multiple, randomized, clinical trials (RCTs)—especially those with strong effect sizes, sound methodology, and strong execution. Like all systemic reviews, this guide does not provide a standard of care. Rather, it is useful as a tool for physicians and nurses to guide clinical preventive practices, such as vaccines, laboratory practices or pharmaceuticals for specific conditions or diseases.
While the science for synthesizing research results has exploded, the methods for linking evidence to recommendations are less well developed and more varied. Different groups use different processes for devising recommendations. However, there are some basic principles applicable to the process, nuances notwithstanding.
First, a major topic of interest or question is determined. Then a thorough search of the literature is conducted, with the evidence ranked according to the strength of the evidence. In general, the best evidence is used. This includes evidence from RCTs, non-RCTs, cohort studies, case-control studies, crossover studies, cross-sectional studies, case studies, or pre-post measurement. Expert opinion is often excluded.
Once the evidence has been summarized, there are different methods for coming up with recommendations which are too numerous to detail here. In general, they address how the study was designed, how the study was conducted or executed, the strength of the analysis, statistical power, and effect size, among other factors. Regardless of the methods, the recommendations for systematic reviews are governed by a unique set of rules for how scientific articles are rated and ranked for evidence. These rules are used to evaluate all of the scientific articles that address a particular topic of interest. Often, the reviews include summaries of what the science says and give appropriate recommendations as well as the delineation of any research gaps.
For example, in May 2006, the Council on Scientific Affairs of the American Dental Association (ADA) released a literature review on professionally applied topical fluoride.2 The panel graded the evidence by the type of study and classified recommendations based on the type of evidence. The presence of multiple RCTs provided the highest level of evidence, and correspondingly was given the highest level of recommendation. One of the recommendations stated that fluoride gel is effective in preventing caries in school-aged children. Another stated that for patients with low caries risk, the incremental benefit of topical fluoride is not realized.
OPTIONS IN EVIDENCE-BASED DENTISTRY
Bridging the gap between research and dental practice, evidence-based dentistry attempts to collect and evaluate the science to render it as clinically relevant as possible. For the interested practitioner, there is a multiplicity of options available for accessing evidence-based information:
- The journal Evidence-Based Dentistry.3 According to its Web site, the aim of the journal is to “alert clinicians to important advances in the practice of dentistry and its specialist areas” by selecting from the biomedical literature those original and review articles whose results are most likely to be true and useful. These articles are summarized in value-added abstracts and commented on by experts. A recent issue included a review of topical fluoride; whether flossing reduces interproximal caries; whether professional mechanical plaque removal was effective in treating periodontal disease; and whether primary-care screening programs were cost effective in preventing oral cancer.
- The Centre for Improving Oral Health through Evidence-Based Dentistry is the leading center for evidence-based dentistry. Located in the United Kingdom, it was established by the visionary dentist Nigel Pitts, director of the Dental Health Services Research Unit at the University of Dundee, and his team as part of the Virtual Center for Improving Oral Health. The center identifies particular topics of interest in dentistry and synthesizes quality best evidence on dental interventions and dental care of importance, collaborating with organizations such as the International Association of Dental Research (IADR), and the World Dental Federation (FDI), as well as with the ADA. It also provides training on evidence-based techniques to dentists who want to use or understand the process.
- Other resources for evidence-based dentistry are available in the United States at the Agency for Healthcare Research and Quality (AHRQ). AHRQ, through its Evidence-Based Practice Centers (EPCs), sponsors the development of evidence reports and technology assessments to enhance the quality of health care. The centers evaluate science-based information on common, costly medical conditions and new medical technologies. The EPCs systematically review and analyze relevant scientific literature on topics assigned to them by AHRQ, issuing reports and assessments for medical practice. EPCs often use partnerships or collaborations with other medical and research organizations to enhance health care quality and go through a peer-review process. The reviews are used by individual health plans, providers, and purchasers to guide improved health care practice.
- In addition to the Guide to Clinical Preventive Services, there is another government-sponsored guide for community level, not individual level, preventive services. The Guide to Community Preventive Services is an initiative of the Department of Health and Human Services and a 15-member independent panel of experts. This guide reviews community interventions for specific risk behaviors or conditions, such as physical activity and smoking reducing specific diseases, injuries, or impairments, or addressing environmental conditions. They also have reviewed community-level outcomes for community water fluoridation and school-based sealant programs. The interven-tions must relate to the measurement of a particular health outcome and there is an explicit process for translating evidence-based reviews into recommendations. Because community-level interventions generally don’t have RCTs, this community guide uses a less rigorous criteria for evaluation of evidence than the previously describe Guide to Clinical Preventive Services.
- The Cochrane Collaboration4 has the most detailed and comprehensive library of reviews for both medical and dental issues. For oral health, this includes a list of activities such as prevention with mouthwashes, flosses, and toothbrushes, as well as a variety of clinical procedures, such as tongue scraping for treating halitosis, evaluation of various interventions for replacing missing teeth with bone augmentation or implants, and treatment of oral candidiasis.
- The use of common electronic dental records in dental schools means that patient outcomes for certain procedures or treatments can be gleaned from various sources. Some dental schools, including New York University, the University of Florida, the University of Washington, and the University of Alabama, have research-based practitioner networks. One of the largest of these networks is Practitioners Engaged in Applied Research and Learning (PEARL), a project of the National Institute of Dental and Craniofacial Research (NIDCR), which comprises dentists who have the interest in recognizing and applying the scientific process to the procedures that are conducted each day in practice.5 Dentists are invited to become “Network Practitioner-Investigators” through this network. Practitioners are required to have sufficient staffing, electronic records, and an understanding of whether their patients meet the clinical entry criteria for particular studies. The PEARL network is evaluating the validity of both accepted clinical procedures, and evaluating new and emerging processes and procedures. The research networks will have hundreds of dental practices to include for evidence-based dentistry, all while complying with HIPAA standards. This will allow the practicing dentist to be the font of research for dentistry.
CAVEATS AND CONCLUSIONS
As with anything else, practitioners will have to use discretion for interpreting the results of this evidence-based review. While lack of evidence does not mean lack of effectiveness, it seems clear that one of the challenges in evidence-based dentistry is this: many topics do not have a sufficient body of clinical research or sufficient size of study population to evaluate the effectiveness of a particular procedure or process. Moving forward, electronic dental records are likely to facilitate the process for summarizing patient outcome data, and thus the ability to create larger clinical outcome data over time.
Additionally, since different reviews have different rules, you cannot compare one type of review to another. For example, in most cases you can’t compare a review by the Cochrane Collaboration to one for the Guide to Community Preventive Services. The decision rules for evaluating each of these are quite different, with the Cochrane Collaboration using RCTs for its highest recommendation, while community level interventions are ranked from evidence that does not generally include these types of trials. In general, the strength of the evidence of effectiveness is directly linked to the strength of the recommendation (See Sidebar).
Using evidence-based dentistry could be a good tool to evaluate what you do in your practice, now as well as the future. The literature is constantly being reviewed, so these resources should be checked at least periodically. They do not substitute for reading and keeping up to date with dental literature. As with other practice-management tools, talking with your patients about their perceptions and needs will help to guide your treatment decisions. Rather than simply acting as a yardstick to measure evidence, these evidence-based dentistry reviews are another solid practice-management tool to assist you in making the best possible decision, one that is customized for each patient and based on the best possible information available. Because providing the best quality care is what we all want for our patients, using evidence-based dentistry is another tool in our armamentarium that will help us to provide that care. But, remember, it is neither a cookbook to determine every single practice in dentistry nor a standard of care. Rather, it is a summary of the body of scientific literature at a given point in time about a particular area of practice.
Ultimately, it is the clinician who must decide what is best for his or her patients. Evidence-based dentistry can be of great help in the decision-making process to help ensure the best outcome for patients.
1. United States Department of Health and Human Services; US Preventive Services Task Force. Guide to Clinical Preventive Services. Washington, DC: 1989. Available at: http://www.odphp.osophs.dhhs.gov/pubs/guidecps/uspstf.htm. Accessed November 22, 2006.
2. American Dental Association Council of Scientific Affairs. Evidenced-based clinical recommendations for professionally applied topical fluoride. J Am Dent Assoc. 2006;137(Special Insert). Available at: www.ada.org/prof/resources/pubs/jada/reports/report_fluoride _exec.pdf. Accessed November 22, 2006.
3. Evidence-Based Dentistry. Available at: www.nature.com/ebd/index.html. Accessed November 22, 2006.
4. The Cochrane Collaboration. Available at: http://www.cochrane.org. Accessed November 22, 2006.
5. National Institute of Dental and Craniofacial Research: Practitioners Engaged in Applied Research and Learning (PEARL). Available at: http://www.web.emmes.com/study/pearl/become/become.htm. Accessed November 22, 2006.
HIERARCHY OF SCIENTIFIC STUDIES USED FOR EVIDENCE-BASED REVIEWS*
Randomized, controlled clinical trial (RCT): Participants are divided into groups, assigned randomly to either a control or experimental group. There is intention to treat with the experimental group who receives the intervention or treatment, while the control group receives a placebo or standard intervention. These groups are followed up on for the outcomes of interest.
Controlled clinical trial: Similar to an RCT, but the assignment of subjects is based on a non-blinded or non-randomized process into either control or experimental groups.
Case-control study: Compares people with a particular clinical condition, or cases, to people who do not have the condition, called controls. They are evaluated to determine what similar or different exposures that they might have.
Cohort study: Two different groups or cohorts are compared; one group that received the exposure to another that did not to assess the outcome of a particular type of treatment or intervention.
Case-series: Collection of individual case studies without a control group.
Crossover study design: Studies in which two types of treatments or therapies are given to the same group of patients.
Cross-sectional study: The observation of a defined population at a single point in time or in a specified time interval. Exposure and outcome are determined simultaneously.
Pre-post measurements or assessments: Studies in which subjects are measured before a treatment or intervention and then after to assess what the outcome of the treatment or intervention is.
* Ranked from most to least rigorous and clinically reliable.