PubMed has online Tutorials (http://www.nlm.nih.gov/bsd/disted/pubmed.html) and YouTube tutorials that walk through the steps of a search and explain each PubMed feature and tool so users understand how to conduct a search and the language for how information on the database is indexed. For example, PubMed and MEDLINE use the MeSH (Medical Subject Headings), a controlled vocabulary thesaurus or indexing language, which allows there to be consistency in the key terms assigned to the articles indexed from the 5,600 journals. Each reference is associated with a set of MeSH terms that describe the content of the item.
The MeSH Database can be accessed from the PubMed home page (Figure 1). By opening this browser, a word(s) can be entered in the search box. Although when typing in ‘stannous fluoride’ a pull-down list of other terms appears, do not mistake these for MeSH terms (Figure 2). They are just terms others have typed in.
Figure 2. MeSH Database Search Page.
Click on Search and the MeSH indexing term(s) that is/are used appear (Figures 3). Next, click on Tin Fluorides since this appears to be the applicable term. Additional information is displayed related to subheadings, different entry terms, previous indexing and where the term is structured in the hierarchical "MeSH tree" (Figure 4). This is a helpful tool when an original search does not yield enough results. It will often provide additional terms related to a search, which may lead to more relevant information. For example, in searching for evidence on stannous fluoride, type in the term ‘stannous fluoride’ to determine if it is the correct MeSH term.
Figure 3. MeSH Database Search – Stannous Fluoride Results.
Figure 4. Stannous Fluoride / Tin Difluorides Entry Terms and MeSH Categories.
The results from using the MeSH Browser indicate that Tin Fluorides (vs. stannous fluoride) is the MeSH indexing term, however stannous fluoride is an entry term. If there were an inadequate number of citations then according to the MeSH Tree, the search would need to be broadened using the term Fluorides – one level up from Tin Fluorides.
When conducting the same search using the term Sodium Fluoride, the term Sodium Fluoride is identified as the MeSH term. Again, if there were an inadequate number of citations then according to the MeSH Tree, the search would need to be broadened using the term Fluorides – one level up from Sodium Fluoride.