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Dental Medicine Resources: Find Evidence

Information Resources & Research Help for Dental School students

PICO Question

In children with dental caries, will fluoride varnish, as compared to no fluoride varnish, result in a decreased incidence of caries?

Levels of Evidence

You will see many different versions of the evidence hierarchy pyramid.  However, they all have commonalities:

Meta-Analysis / Meta-Synthesis / Systematic Review: These are sources of high level evidence as they are analyses of existing research. They are generally at the top of the evidence pyramid. Be sure to look at inclusion/exclusion criteria and forest plots to appraise the quality of the source.

Clinical Practice Guideline (CPG): CPGs are also high level evidence. They are put in place by those who have analyzed existing research on a topic in order to develop the guideline.

- Randomized Controlled Trial (RCT): RCTs are also high quality evidence. RCTs are often ranked right below meta analyses, meta syntheses, systematic reviews, and CPGs. Randomization increases the quality of the source and reduces bias.

- Experimental Study: Experimental studies rank below RCTs, but are still good sources of evidence. In order to have an experiment you must have control, manipulation, and randomization.

- Non-experimental/Descriptive/Correlational: These rank below experimental studies, but above qualitative studies.

- Qualitative Study: Qualitative studies often have fewer participants and are often focused on the experience of something.  Although qualitative studies may not be at the top of the pyramid, they are very important to some topics. For instance, a qualitative study would be very helpful for topics such as the experience of having a premature birth or the experience of going through cancer treatments.

- Expert Opinion: Expert opinions are lower level evidence.

Cochrane Library

The Cochrane Collobaration's mission is to "promote evidence-informed health decision-making by producing high-quality, relevant, accessible systematic reviews and other synthesised research evidence."

Authors of Cochrane systematic reviews follow a publication process that is well-known as the benchmark for systematic reviews.

***Note: The Library has a limited number of log-ins for the Cochrane Database and EBMR

ADA Center for Evidence-Based Dentistry

According to the ADA Center for Evidence-Based Dentistry website, its mission is to appraise and disseminate the "best available scientific evidence on oral health care" and help practictioners "understand and apply the best available evidence in their clinical decision-making."

***Note: This resource is updated on a quarterly basis, so check PubMed in case more updated evidence is availabe.


"PubMed comprises more than 24 million citations for biomedical literature from MEDLINE, life science journals, and online books."

***Note: If you are off-campus, navigate to PubMed from the library's homepage to link out to full-text options.