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Dental Hygiene: EBDM #2 Acquire

Toolkit for Dental Hygiene

Boolean Operators

  • Databases require mathematical rules in order to function
  • These mathematical functions are known as Boolean Operators
  • There are different operators, the most commonly used are AND & OR
  • Boolean operators allow for the combination of concepts in databases
    • OR expands a search
    • AND focuses a search


  • When searching you sometimes need to think of synonyms for a concept in order to capture all the information on that concept
  • For example, to find something on the topic of electronic toothbrushes, you may also want to include brand names
  • Always put brackets around terms you are OR'ing ("electric toothbrush" OR sonicare)


  • AND is used in searching when you want the results to contain all the concepts important to your research
  • For example, if you're interested in the difference between electronic toothbrushes and manual toothbrushes your search may be "electronic toothbrush" AND "manual toothbrush"
  • AND is used to narrow your search
  • If your results are too small, try removing a concept that you AND'ed

For more help, see the How to Search in Health Sciences LibGuide

Tutorial Link


Medical Subject Headings (MeSH) is the controlled vocabulary used in the PubMed and MEDLINE databases. Controlled vocabulary (or subject headings)

  • Pre-defined, specific words, used to describe the article
  • Details the subject matter and publication type of the article
  • Less flexible to search - need to use exact MeSH term
  • When used in a search, only looks in the MeSH field (rather than the title or abstract)

MeSH is not needed in a PubMed search. Usually a keyword search (which searches term in the title/abstract field) is good enough. However, MeSH can be helpful if you aren't finding the results you want.

To find MeSH, you need to search terms in the MeSH database in PubMed

Creating a search with PICO

Search Concept 1 (Problem/Population) Search Concept 2 (Intervention) Search Concept 3 (Comparison) Search Concept 4 (Outcome)
Keyword/Synonyms Keyword/Synonyms Keyword/Synonyms Keyword/Synonyms
MeSH/Subject Headings MeSH/Subject Headings MeSH/Subject Headings MeSH/Subject Headings

Use OR between synonyms and like terms

Use AND between search concepts