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

Evidence-Based Decision Making

When investigating ergonomic interventions, oral health professionals should incorporate this important process to increase the likelihood of success.

This course was published in the April 2015 issue and expires April 30, 2018. The author has 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. Define evidence-based dentistry as it applies to ergonomics.
  2. Describe the steps used in the practice of evidence-based dentistry.
  3. Determine if an article is best evidence through consideration of its research design.
  4. Evaluate the value of an article through the application of key statistical results.

Since the mid 1990s, evidence-based dentistry (EBD) has been touted as a way to improve clinical care and treatment in dentistry.1 EBD is an approach to oral health care that integrates clinically relevant scientific evidence with the practitioner’s clinical expertise and patient treatment needs and preferences.2,3 Evidence-based decision making can be applied to all facets of practice, including the process of choosing an appropriate ergonomic intervention.4

Ergonomics is often used to reduce or prevent musculoskeletal disorders, which are common among oral health professionals. On average, 66% of dental practitioners experience musculoskeletal pain at some point during their careers.5 Oral health professionals may be taught how to safely and effectively position themselves and patients through the principles of ergonomics. But how often do practitioners’ behaviors change when new ergonomic evidence or equipment is introduced? The practice of EBD can be applied in this situation.

Some of the advantages of EBD include improving performance and minimizing the level of experience required to develop clinical judgment. On the other hand, barriers to implementation remain, such as lack of time to search and read; the need to develop new skills (eg, efficient search skills, critical appraisal, and statistical comprehension of the results); and the lack of generalizability of research articles that offer summaries and/or guidelines based on current literature.6 Even when literature exists, practitioners always should ask, “Is the interpretation and recommendation based on the best possible evidence for practice?” In articles reporting the results of one study, authors rarely make clinical recommendations; this is left up to the reader. As such, oral health professionals need to be able to evaluate research within an EBD framework. When making changes in practice, clinicians need to follow the appropriate steps.

EBD is based on the application of scientific research, clinical expertise, and consideration of patient values and expectations.7 These factors have equal footing in decision making. In the case of ergonomics, the dental practitioner is the “patient” trying to prevent, reduce, or eliminate musculoskeletal problems that develop due to practice.

The five steps of an evidence-based process include:

  1. Develop a focused question based on the need for information
  2. Conduct a search for the best possible evidence
  3. Appraise the evidence for applicability and quality
  4. Apply evidence based on clinical expertise and knowledge of patient values and expectations
  5. Evaluate the effectiveness of the information in actual daily practiceThe sidebar included with this article provides a practical look at implementing the evidence-based process.


The purpose of writing a question is to narrow the focus of the search, and PICO (person, intervention, comparison, outcome) should be used. “Person” refers to the patient’s or population’s characteristics, including the description of the problem. Intervention is the patient management technique implemented, such as the use of equipment. In ergonomics, new instruments/techniques adopted by the clinician to reduce the strain on his or her musculoskeletal health will serve as the intervention. The outcome is focused on how well the intervention alleviated the sign or symptom during the performance of a specific task.

Using PICO helps clinicians formulate an answerable clinical question. There is not always a need for comparison. In the sidebar example, the comparison line could have been left empty, which would indicate the clinician is only interested in learning about lightweight instruments. Each part of PICO?provides keywords that can be used in a literature search to support its speed and efficacy.


The next step is to search for the best possible evidence. There are different types of evidence based on research design. The evidence-based pyramid demonstrates the hierarchy of information (Figure 1). The higher levels of the pyramid represent the most likely sources of high-quality research. Systematic reviews are at the top of the pyramid because they often overcome many of the limitations of single studies. By providing comprehensive analyses, systematic reviews summarize the available research and offer recommendations for practice. The strength of a systematic review depends on the level and amount of research that is currently available. The best possible systematic review is composed of randomized controlled trials (RCT). Also, systematic reviews are not always available. The next level of evidence is a single-study RCT.

Evidence-Based Decision Making for Ergonomic Interventions
FIGURE 1. Hierarchy of evidence from least controlled for bias to most controlled for bias.

An evidence search begins by plugging in the keywords determined by PICO into an electronic database (such as PubMed, Dentistry and Oral Sciences Source, or EBSCOhost). Developing quality search skills is important to finding evidence. The best place to begin is PubMed (, a free search engine developed by the United States National Library of Medicine and National Center for Biotechnology Information. The PubMed Clinical Queries tool can be used to locate all available research using keywords. Additional search strategies can be found in the tutorials provided at the PubMed site.


Evaluating the collective research gathered during step 2 begins with reading the title and abstract, which will determine whether the article is relevant to the clinical question.

The next factor that needs to be determined is the internal validity of the study.8 Internal validity refers to how well a research study is conducted. Three pieces of information are related to interval validity:

  1. Have subjects been assigned to groups randomly?
  2. Were the investigators as well as the subjects blinded?
  3. Were there few dropouts?

Randomization is considered the most robust method for reducing bias because it helps to create the most homogeneous treatment groups.8 When subjects and investigators are blinded, they are unaware of which subjects are using which intervention. This reduces the risk of bias if investigators or subjects are hoping for specific outcomes. Computerized randomization that is concealed from investigators is one of the best methods of randomizing and blinding study subjects/investigators. A study that has at least 85% of its participants complete the study is the benchmark.8 A study demonstrates good internal validity when these three criteria are met. While this is a quick way to determine the strength (internal validity) of a research design, a more in-depth discussion is available in the book Evidence-Based Decision Making: a Translational Guide for Dental Professionals.8

External validity is determined by the usefulness of the information to the patient and different areas of practice. External validity is based on how applicable the research is beyond the sample subjects. This is established by understanding who the subjects are, evaluating the statistical results, and noting whether the research occurred in different real-world settings. Table 1 includes some questions to ask when determining external validity.

Individuals who are impacted by the treatment are usually most interested in its positive effects. Achieving a meaningful measure and then showing a positive result make the results important to patients. The p value demonstrates whether the results of each group were different at the end of treatment. A p value less than 0.05 means the difference did not occur by chance. Results should also indicate how large the difference is between the two groups (this is called the effect size of the difference). In other words, is the effect of treatment significant enough to make a difference that is easily seen or felt, thus providing a significant effect in day-to-day practice?


A dental hygienist has developed consistent arm pain in her dominant arm that is not alleviated with rest. She wants to find an effective intervention that may eliminate the need for invasive treatment. She decides that using a different piece of equipment may help. Before she makes a purchase, she wants to know how strong the recommendation would be to change her equipment.

Step 1. The dental hygienist formulates a question: “Will the use of a lighter dental instrument help reduce my arm pain?” Application to the PICO (person, intervention, comparison, outcome) is as follows: P: 42-year-old female dental hygienist with arm pain; I: lighter dental instrument; C: heavier dental instrument; O: reduce pain

Step 2. She uses PubMed to locate any related systematic reviews. After typing in the keywords dental hygienist AND arm pain AND instruments, one article and no systematic reviews are located.

Step 3. The article is “The Effects of Periodontal Curette Handle Weight and Diameter on Arm Pain: A Four-Month Randomized Controlled Trial.”9 The title reveals that the study is an experimental research design that is high on the pyramid. The abstract discloses that dental hygienists with arm pain are the subjects, and they experienced significant improvement in pain scores for the shoulder region when lightweight instruments were used. Before the dental hygienist decides to switch instruments, however, further interpretation of the study design and the results needs to be conducted.

In this study, the subjects were randomly assigned to one of two groups, with each group using an instrument of specific weight and diameter. The subjects and investigators were blinded. The completion rate was 95% (only five subjects discontinued using the intervention).

FIGURE 2. Selected demographic and preintervention characteristics of study participants (N=110).9
*SD: Standard deviation
**0 indicates no pain and 10 unbearable pain

Applying this information about external validity to the patient in the scenario starts with the question: Does the patient from the PICO qualify for the study? Reviewing the modified table (Figure 2) provides characteristics of the subjects at a glance and answers the question “Is the patient similar or too different for the results to apply?” The dental hygienist falls within the age range of subjects in the study, and also matches the mean hours per week and measure of pain preintervention.

FIGURE 3. Post-intervention results.9

Where the subjects differ is in their reports on the exit survey, in which higher ratings were obtained for the light instrument with wide handle. From these means (standard deviation), a secondary outcome, the effect of the size of each group can be calculated by dividing the mean change by the standard deviation (SD) for the change (Figure 3). The interpretation of these results implies minimal negative effect for the heavy-handle group and moderate positive effect for the light-handle groups.10 So before the treatment begins and while the treatment is ongoing, the dental professionals did not differ in their daily tasks; the only difference was the instrument they were using. After completing the study, statistical difference was noted in favor of the light-handle group with strong internal validity. The external validity or generalizability comes from the experiment being carried out in various dental clinics and not in one laboratory setting, and the likelihood of finding the same outcome among individuals with similar characteristics.

What characteristics might best describe the individual most likely to benefit? A general linear model (Figure 4) is one way to predict outcomes in the future. In this study, the adjusted models included age, sex, occupation, and mean hours of instrument use per week. Specifically, it determines if the amount of change in pain can be predicted based on the instrument size and weight. It creates a model for future prediction. Figure 4 provides mean pain score changes with standard error of the mean (SEM) for the two groups and the results of the regression analyses for different aspects of the upper extremity. The SEM is the SD related to taking measures repeatedly. The SEM means that the scores are reliable—less than one has very small variations.

FIGURE 4. Adjusted* regression models comparing effects of instrument on change in pain scores in right-upper extremity regions.9
*Adjusted models include covariates age, sex, occupation, and mean hours of instrument use per week

The only significant model found is the relationship between change in pain scores and pain in the shoulder. Beta coefficient means the amount of change in the dependent variable of pain that is expected if the new instrument is put into use. The confidence interval (CI) for beta means 95% surety that the true value for beta is between 0.02 and 0.324. While the model is significant, the change is very little: 0.18. Using the 95% CI, this change could be as small as 0.02 or as large as 0.324. While the light- and wide-diameter instrument changed the pain experienced in the shoulder for those individuals who used it, the effect size was considered modest and the pain was not completely eliminated. Because the treatment was effective, the next choice is to decide if the amount of change is enough to warrant the use of a new piece of equipment.

Step 4 and Step 5. As this was a 4-month study, the dental hygienist must give the intervention at least this much time to work. If the time is cut short and the treatment does not alleviate her pain, it will be unclear whether the new instrument was the problem or if the treatment was not given enough time for results to occur.


The fourth step is to apply the results to clinical practice, providing enough time to determine the results. Evaluating whether the findings are relevant to the patient, problem, or question is key to successful application.11

The final step is to assess the process, performance of the clinician, and the outcomes of the treatment provided. This process can include evaluating the outcomes relative to the health/function of the patient, patient satisfaction, and input into the decision-making process, as well as an examination of the EBD process by the clinician.11


EBD is integral to improving patient care and the efficacy of treatment, and proper ergonomics is key to maintaining clinician health. Ergonomic principles have been developed, but they are often not enough to help oral health professionals change the way they practice. The EBD process may help clinicians evaluate ergonomic interventions, enabling them to make the best decisions on the appropriate intervention based on solid evidence. Active involvement in EBD (searching for evidence, reading it, interpreting the results, and applying them) supports oral health professionals in their decision-making processes.


  1. McGlone P, Watt R, Sheiham A. Evidence-based dentistry: an overview of the challenges in changing professional practice. Br Dent J. 2001;190:636–639.
  2. American Dental Association. Policy on Evidence-Based Dentistry. Available at: Accessed March 18, 2015.
  3. American Dental Association. Evidence-Based Dentistry. Available at: Accessed March 18, 2015.
  4. International Ergonomics Association. Definition and Domains of Ergonomics. Available at: Accessed March 18, 2015.
  5. Valachi B, Valachi K. Preventing musculoskeletal disorders in clinical dentistry: strategies to address the mechanisms leading to musculoskeletal disorders. J Am Dent Assoc. 2003;134:1604–1612.
  6. Madhavji A, Araujo EA, Kim KB, Buschang PH. The attitudes, awareness, and barriers towards evidence-based practice in orthodontics. Am J Orthod Dentofac. 2011; 140:309–316.
  7. Straus SE, Richardson WS, Glasziou P, Haynes RB. Evidence-based Medicine: How to Practice and Teach EBM. 3rd ed. New York: Elsevier; 2005.
  8. Forrest JL, Miller SA, Overman P, Newman MG. Evidence-Based Decision Making: A Translational Guide for Dental Professionals. Baltimore: Lippincott Williams & Wilkins, 2008.
  9. Rempel D, Lee DL, Dawson K, Loomer P. The effects of periodontal curette handle weight and diameter on arm pain. A four-month randomized controlled trial. J Am Dent Assoc. 2012;143: 1105–1113.
  10. Cohen J. Statistical Power Analysis for the Behavioral Sciences. 2nd ed. Hillsdale, Michigan: Lawrence Erlbaum; 1988.
  11. Forrest JL, Miller SA. Evidence-based decision making. Dimensions of Dental Hygiene. 2005;3(9):12.

From Dimensions of Dental Hygiene. April 2015;13(4):69–72.


Leave A Reply

Your email address will not be published.

This site uses Akismet to reduce spam. Learn how your comment data is processed.

This website uses cookies to improve your experience. We'll assume you're ok with this, but you can opt-out if you wish. Accept Read More

Privacy & Cookies Policy