Reconnecting Practicing Hygienists with the Nation's Leading Educators and Researchers.

Developing a Critical Eye

This course was developed in part with an unrestricted educational grant from Colgate Oral Pharmaceuticals.

This course was published in the February 2010 issue and expires February 2013. The authors have no commercial conflicts of interest to disclose. This 2 credit hour self-study activity is electronically mediated.



After reading this course, the participant should be able to:

  1. List the different types of published scientific literature.
  2. Discuss the concept of evidence-based practice.
  3. Understand the different components included in a published scientific article.
  4. Evaluate the quality of a clinical research article.
  5. Apply evidence-based decision making to patient care.


In the first article “Keeping Current” of the six-part series—Leveraging Scientific Evidence to Improve The Oral Health Practices of Patients—that appeared in the February issue of Dimensions, Dr. Forrest and Dr. Newman discussed how to find and use scientific evidence to make improved clinical decisions in practice. Throughout our professional careers, we will need to review the published scientific evidence regarding certain trends, products, technologies, or medications that we are using in practice. In the second article of this series, Dr. Fine and I explain the elements that are included in a published oral care clinical study and the methods used to analyze whether the scientific evidence is valid based on what the hypothesis or objective of the study states. We hope this article helps you in your own literature search and review. —Christine A. Hovliaras, RDH, BS, MBA, CDE, Guest Editor

Clinical research publications play an important role in evidence-based dentistry by assisting dental professionals in making practical decisions about the technologies and therapies used to diagnose and treat oral diseases. Best clinical practices must be based on quality research in order to ensure that their use will help patients achieve optimal oral health. Many different categories of published research are available and their impact on evidence-based practice is unique. Understanding the various components of clinical research publications and how to review these publications will help the practitioner determine their impact on clinical practice.

There has been an explosion in scientific information over the past two decades, including the genome project and stem cell research, which have revolutionized biomedical sciences. The research demonstrating the connection between systemic disease and oral conditions now requires the dental practitioner to take a larger role as a health care provider. Determining which sources provide the highest level of evidence-based information can be challenging. Sources of evidencebased research vary from the highest level impact to the lowest level impact research.1-4 See Table 1 for an explanation of the different types of evidence-based resources.

Components of a Clinical Study Publication

The task of consistently reviewing clinical study publications is not always easy or exciting. But understanding the components of a clinical research publication—from the title to the conclusions—provides insight into how to logically interpret the research and determine if it is valid.

The Title of a clinical study publication should accurately reflect what the study is about and the research that has been conducted to test the hypothesis. Authors should be listed with their affiliation (college/university, private research corporation, oral care corporation) based on the time and effort they have contributed to the published work. Some groups have a consistent interest in a particular area of study (ie, microbiology, systemic disease), therefore, the reader will know the paper has a certain level of quality. For example, in the Authors section of Table 2, the co-authors are from the University of Rome, Colgate-Palmolive Company, Boston University School of Dental Medicine, and LRM Statistical Consulting. The authors listed first have the greatest responsibility in conducting the research while others may have been responsible for different tasks required by the study.

The Abstract is a short paragraph that provides a summary of the scientific paper. This should be read first in order to ascertain what the study objective(s) are, the types of methods used, the results of the findings, and the conclusions that the practitioner can bring back to practice. The Abstract should be clear, concise, and provide the details that the reader needs. The Abstract will not show shortcomings of the study, thus, the reader still needs to review the entire paper.

The Introduction of the published article includes three different areas of importance. The first is a literature review of the objective being researched and the supporting documentation that has been published on this topic. Second, it describes what the current research is regarding the objective of the paper. Third, the Introduction provides a review of what has been discussed in the article and how this information, product, or technology can be applied in practice. The hypothesis should be clearly stated in the Introduction.

The Materials and Methods section of an article provides a very detailed overview of how the study was conducted. The details provided in the Materials and Methods section should include: information on the participants used in the study; the examination processes including indexes, diagnostic tools, and technology; the phases of the study; the research methodology and protocols used; a timeline for interventions; the data collection methods used; and detailed procedures for statistical analysis. This information helps other dental professionals use these experimental standards and repeat them in future clinical trials. Attention to the exclusion criteria and inclusion criteria of a clinical trial is required to understand if the results can be applied to a small defined population or broad groups of patients.

In the Results section, the findings of the study should be discussed without bias. The reader must ask if the statistical significance of the therapy or product will show clinical significance. Statistical significance is the ability of one treatment to outperform and show a significant outcome versus another treatment and that the associations between groups did not occur by chance.5 Clinical significance is when a treatment is able to show a visual difference versus another treatment group. For example, if a product is evaluated for efficacy in controlling plaque and gingivitis, clinical outcomes such as plaque accumulation and improvement in gingivitis may be evaluated at the 3 month and 6 month treatment periods to see if there is visual improvement. However, if the clinical attachment level is being evaluated and a 0.5 mm gain in attachment is noted, this result may not provide a meaningful long-term outcome of the new treatment.

The major findings of the study as well as their statistical significance are included in the Discussion section. The results of the study should be compared to other research on the same topic. The authors should address the limitations of their study in this section.

The Conclusions section is the final summary of the research study and includes uninterpreted dental inquires and other questions that need to be addressed. The significance of the study’s findings should not be overstated.

Table 2 provides a sample examination of a published research paper.

The Art of Reading and Evaluating Scientific Literature

The trend in dentistry and medicine is to create evidence-based therapies and best clinical practices. It is no longer acceptable to assert that a therapy works in “in the hands of the clinician.” The evidence-based approach to patient care should be grounded in solid clinical research. However, this philosophy of patient care is easier said than done because the clinical research presented in publications does not always provide the practitioner with correct or clinically useful information. In this complex world of biomedical information, many conflicting studies are published and some information is also provided by industry. Therefore, it is the obligation of the practitioner to determine if a study truly provides information that is clinically relevant and beneficial to the patient. In many situations, the practitioner must decide if the results of a study that may be statistically significant also have clinical significance.

Using the Internet is one of the best ways to conduct a literature search and there are numerous search engines to help with the search (see Table 3 for a list). After completing the literature search, practitioners must not only read the articles at face value but evaluate them for quality and possible implementation into practice. Publications take various forms, but all do not dictate evidence for clinical practice. Case reports (usually one or two cases) or case studies (usually a group of cases following a common theme or therapy) provide the reader with some information, but cannot provide definitive evidence for the validity of a specific therapy.

A clinical trial, if well conducted, can provide the practitioner with research that can be used as evidence for making changes in patient care. However, some clinical trials may not be clinically significant for individual patient care. It is then up to the practitioner to decide if the research being presented can serve as evidence of certain clinical therapies.

Well-designed systematic literature reviews on a specific therapy or topic, called Cochrane reviews, break down the various clinical trials published about a specific therapy and provide guidance to the practitioners on the validity of the therapy or agent being evaluated. If such reviews for a particular agent, product, or therapy are not available, then the reader must make his or her own evaluation and assessment of the research.

Reading and evaluating the scientific literature is an art but neither a degree in statistics nor a PhD is needed to make a fair assessment of a paper. The first step is to just read through the paper and arrive at a general understanding of what the author is trying to prove. Keep in mind that a quality research paper is answering a very specific question. The author may try to impart a more global aspect for his or her research. For example, an author may claim that a mouthrinse designed to decrease gingivitis also benefits patients’ overall systemic health.

The reader also needs to remember that the author may equate statistical significance with clinical significance. It is up to the reader to discern if there is clinical significance to the product or therapy. Also because it is rare that two active therapies or products are matched head to head, the reader must do some work to decide if another product not tested is better or worse. Would another mouthrinse have achieved similar results if used in the researcher’s protocol?7

The reader must also be aware that negative results are rarely published. The outcome for most studies is that there was statistical significance between the groups or therapies tested.

After having read the article and contemplated some of the issues just discussed, there are more challenges. Five questions need to be answered in order to effectively judge whether the study should affect clinical practice.

  1. What was the type or level of disease treated or prevented? For example, are the results of a gingivitis study relevant to periodontitis patients?
  2. Was the methodology or treatment provided in the study practical for private practice? Did the study require many hours of treatment that would be impractical or too costly in practice?
  3. Can the results be applied to those individuals excluded from the study if they are treated in private practice? If the study excluded smokers, patients who have diabetes, and pregnant women, would the treatment still work for these individuals?
  4. How long did the study last? If the study was only for 3 months would the results be maintained for 1 year or 2 years or do patients go back to baseline or in reverse? Did the study have to be conducted for a long time to realize an effect from the treatment?
  5. Are there any built-in biases that may account for the outcome of the study? Who funded the study? Was it the company manufacturing the product, the federal government, or private funding? Did the author have a financial interest in the product?

In Conclusion

In today’s world of instant information and advancing science, dental professionals need to develop confidence in searching and obtaining literature in order to develop evidence-based approaches to dental hygiene practice. These skills provide the keys to effectively evaluating scientific evidence and incorporating the information into everyday practice, where patients will be the true beneficiaries.


  1. Forrest, JL, Mullin SA. A practical guide for incorporating evidence into dental hygiene practice. Access. 2007;21(10):12-18.
  2. Daniel S, Harfst S, Wilder, R. Dental Hygiene Concepts, Cases and Competencies. 2nd ed. St. Louis: Mo: Mosby Elsevier; 2008:52-61.
  3. Darby M, Walsh P. Dental Hygiene Theory and Practice. 3rd ed. St. Louis, Mo: Saunders Elsevier; 2009:10-12.
  4. Daly J, Willis K, Small R, et al. A hierachy of evidence for assessing qualitative health research. J Clin Epidemiol. 2006;60:43-49.
  5. Greenstein G. Clinical versus statistical significance as they relate to the efficacy of periodontal therapy. J Am Dent Assoc. 2003;134: 583-591.
  6. Docimo R, Montesani L, Maturo P, et. al. Comparing the efficacy in reducing dentin hypersensitivity of a new toothpaste containing 8.0% arginine, calcium carbonate, and 1450 ppm fluoride to a benchmark commercial desensitizing toothpaste containing 2% potassium ion: an eight-week clinical study in Rome, Italy. J Clin Dent. 2009;20:137-143.
  7. Houle T, Stump D. Statistical significance versus clinical significance. Semin Cardiothorac Vasc Anesth. 2008;12:5-6.

From Dimensions of Dental Hygiene. March 2010; 8(3) Insert.

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