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

Critical Thinking vs Evidence-Based Care

By now, probably numerous patients have asked you if fluoride exposure is associated with low IQ.

By now, probably numerous patients have asked you if fluoride exposure is associated with low IQ. A highly publicized study released in August seemed to conclude that fluoride exposure during pregnancy could adversely affect the intellectual level of children, especially boys.1 Whether you were skeptical of the research or supportive, it was an attention-getter. Yet as oral health professionals, it’s incumbent upon us to view science as the search for truth. That search involves several steps, and not just reading a headline.

Let’s start by reviewing the concept of evidence-based dentistry (EBD). The American Dental Association defines EBD as “an approach to oral health care 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.”2 Note that there are three equally important aspects to EBD:

  1. Current, clinically relevant evidence/research
  2. The expertise and experience of the oral health professional
  3. The needs of the patient

When EBD first became commonplace in the late 1990s, one of its pioneers, Michael Newman, DDS, explained the concept in a way I will never forget. He said that while it’s important to examine the evidence or research, ”… EBD is not dentistry solely based on the evidence.” Clinicians and patients play a role as well. And the role of clinicians is to critically evaluate studies and their findings to determine useful and accurate applications.


That takes us back to the study on fluoride noted above. How would you use your evidence-based training to evaluate the conclusions of this study? First, read the study in its entirety. The abstract and conclusion can provide an overview, but it’s important to understand how the study was conducted. Does the methodology make sense? Are there questions about how the study was conducted that might cast doubts on the conclusion? The American Dental Hygienists’ Association developed a statement regarding the study immediately after it was published.3 In it, several limitations of the research were discussed. Next, use your expertise and knowledge to ascertain if your experience supports the conclusion. Does this study seem to be an outlier? Do other studies support the findings? Have you seen results in your practice that might not support the conclusions? Finally, determine what would be best for the individual patient. Is the expectant mother at high risk for caries? All of these questions—and others–—warrant your attention as an oral health professional, so you can then advise your patients.

Evidence-based care is here to stay, yet it’s important that we use the evidence-based approach as intended. We also need to realize that not all “evidence” is the same. This is why our training on how to think critically is so significant, and this is what patients rely on us to provide.

Jill Rethman, RDH, BA
Editor in Chief

Dimensions of Dental Hygiene published a critical analysis of a recent study that linked fluoride to kidney and liver function that is available at:​.


  1. Bashash M, Thomas D, Hu H, et al. Prenatal fluoride exposure and cognitive outcomes in children at 4 and 6-12 years of age in Mexico. Environ Health Perspect. 2017;125:097017.
  2. American Dental Association’s Center for Evidence-Based Dentistry. About EBD. Available at:https:/​​/​​​​en/​​about. Accessed October 22, 2019.
  3. American Dental Hygienists’ Association (ADHA). ADHAStatement Regarding a Study Linking Maternal Fluoride Exposure during Pregnancy and the IQ Scores of Their Children. Available​​resources-docs/​​Press_​​Release_​​ADHA_​​JAMA_​​response.pdf. Accessed October 22, 2019.


From Dimensions of Dental Hygiene. November 2019;17(10):6.

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