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Evidence-Based Dentistry

Resources to support the practice of EBD

Using a PICO to create a Search Strategy : Tips

Creating a Database Search Strategy Based Upon PICO (T)

Note: This type of strategy works for larger databases such as PubMed, Cochrane Library, etc. Smaller useful banks of evidence such as the ADA Evidence Database or the National Guideline Clearinghouse may be more suitable for category browsing.

  1. Do not search for your complete PICO sentence
  2. Search for your PICO terms 
    1. Leave out adjectives, connecting words, punctuation, etc.
    2. Leave out any words that can be implied or included by other search terms
  3. Identify any synonyms or broader terms that closely relate to your terms
    1. Find useful synonyms by:
      1. Browsing useful discovered articles for their listed keywords
      2. Consult published clinical guidelines
      3. Consult a field specific thesaurus or your textbooks' glossaries
      4. Consult PubMed's MeSH database
  4. Make one change to your search at a time
  5. If filters are available for characteristics such as population demographics, study type, date, etc, use them to refine your results rather than typing them into your search string
  6. Use Boolean coding (AND OR NOT) and punctuation to structure your search
    1. To get fewer results:
      1. Add more terms using Boolean code AND to limit your search
    2. To get more results:
      1. Remove terms to expand your search 
      2. Add synonyms for your terms using Boolean punctuation and Boolean code OR
  7. Consult the ADA Clinical Practice Guidelines Handbook, 2013 Update for more detail and useful search aids

Search Example: Treatment Comparison Question

PICO Question : For patients with halitosis [Patient Problem], are probiotics [Intervention] as effective as chlorhexidine mouthwash [Comparison] in reducing measurable Volatile Sulfer Compound levels [Outcome]?

Identify Important Keywords : halitosis, probiotics, chlorhexidine, mouthwash, volatile sulfur compound

Pubmed Search Part One: halitosis AND sulfur AND chlorhexidine AND probiotics

  • This search includes all of your major terms of interest. It may include exactly the right article, or it may not. 
    • Note: Sulfur is unique enough that it is useful to try searching without the rest of the phrase volatile sulfur compound first. If you find too many irrelevant articles, use the entire phrase.
  • Use Boolean connector AND to tell the database that all articles you find must include each word.
  • This search finds 3 articles, none of them including a direct comparison.
  • To answer your question, you will need to read these, but also look for articles addressing pieces but not all of your question from which to synthesize a conclusion.

Simple PubMed Search Step Two : halitosis AND probiotics AND sulfur

  • Remove one of the comparison words from your search. 
  • This search finds a bit more than 20 articles.
  • This set may include the best articles, or the low number might indicate that this is a good point to add synonyms to one of your terms using Boolean connector OR. A quick check of the MeSH database reveals that there are no useful synonyms or broader terms, so no further searching of this term set would be useful in PubMed.

Pubmed Search Part Three : halitosis AND sulfur AND chlorhexidine

  • Swap the intervention term probiotics with the comparison intervention term chlorhexidine for a new search
  • This search finds a bit more than 50 articles. Again, a quick check reveals that there is no useful synonym, so there is no need to expand the search.

Ideally, you will be able to find the data necessary to perform a thorough analysis in the two separate sets of results.


Search Example : Prevention Question

PICO Question : In adolescent athletes [Patient Population], does the use of facial protection [Intervention] reduce the risk of maxillofacial injury [Outcome]?

Note: Prevention or prognosis questions sometimes do not include a specific Comparison or Control aspect.

Identify Important Keywords : adolescent, athletes, facial protection, maxillofacial injuries

Simple PubMed Search One athletes AND "maxillofacial injuries" AND "facial protection"

  • Search for your core concepts first. 
    • If a concept is available as a preset filter in PubMed, use that after searching instead of entering a term. Age categories are available as filters.
  • Use Boolean coding to organize your search
  • Use quotation marks to enclose the phrases maxillofacial injuries and facial protection. This will ensure that you find exactly those words in that order and reduce irrelevant results.
  • This search finds only one article. You must broaden your search.
  • In this case, you will need to broaden your search by using Boolean to add synonyms for some of the terms. 
    • The other option is to drop a search term, which will result in more but less relevant results.

Pubmed Search Step Two : athletes AND "maxillofacial injuries" AND ("facial protection" OR mouthguard OR "mouth guard" OR "face mask" OR "face guard" OR "Mouth Protectors")

  • A browse of articles reveals that facial protection is a broad category term that isn't very commonly used, so it is a good choice to consider for adding synonyms to your search.
  • Find useful synonyms or names of specific types of facial protection by browsing articles that match your search, consulting a field specific thesaurus such as PubMed's MeSH database, or by looking for specific brand names.
  • Use the Boolean code word OR in between terms to find all articles that contain either or both terms.
    • Boolean is a form of algebra. Use parentheses to ensure that OR groups are searched before AND terms and avoid problems, as shown above. 

Pubmed Search Step Three athletes AND ("maxillofacial injuries" OR "jaw injuries" OR "jaw fractures" OR maxillofacial fractures" OR  "dental fracture" OR "mandibular fracture") AND ("facial protection" OR mouthguard OR "mouth guard" OR "face mask" OR "face guard" OR "Mouth Protectors")

  • Maxillofacial injuries is also a good term to expand upon - while it is more standard than facial protection, it has many subcategories or variants.

PubMed Search Step Four athletes AND ("maxillofacial injuries" OR "jaw injuries" OR "jaw fractures" OR maxillofacial fractures" OR  "dental fracture" OR "mandibular fracture") AND ("facial protection" OR mouthguard OR "mouth guard" OR "face mask" OR "face guard" OR "Mouth Protectors") , with the addition of the Ages : Adolescent : 13-18 years filter

  • PubMed offers a large number of preset filters on the left of your results screen.
  • Click Additional Filters at the bottom of the left screen to get a menu of optional filters. Click all of the ones that you would like to be able to have visible on the active menu. 
  • Check the appropriate age filter for your search to limit your results.