Another valuable tool for conducting an evidence-based search is the Advanced Search Builder, including the Search History feature. This allows you to view all the search strategies that have been run and their results. It also allows you to combine previous search queries using the Boolean operators with new search queries. PubMed may move a search statement number to the top of the History when it’s used again, so the search queries may appear to be out of numerical order. Note when combining searches, the terms do not need to be spelled out again. Instead of typing out tooth erosion OR tooth wear, just type the number of the search, e.g., #1 or #2. Please note, you MUST use the # sign before the actual number.
Figure 7a. Search History on Advanced Search Builder Page.
Using the Advanced Search Builder, you can see that the terms tooth erosion (#1) or erosive tooth wear (#2) were then combined (#3), which then was combined with stannous fluoride toothpaste (#4). This limited the number of citations found to 42 (#5). Next, a search for sodium fluoride and potassium nitrate toothpaste (#6) identified 33 citations. It then was combined with #3 to limit the findings to those related to tooth erosion/erosive tooth wear. The final step was combining searches #5 AND #7 to identify studies that included both types of fluoride toothpaste in relation to tooth erosion (#8). This resulted in retrieving 2 studies. By clicking on 2 under the column Items found, you can see the two studies (Figure 7b).
Figure 7b. Studies Identified Using Advanced Search Builder.
If neither of these studies answers Nathan’s question, then the search needs to be expanded by using broader or more generic terms as mentioned earlier.
As you can see from this search, terms were searched for individually prior to combining them. This allows the user to see exactly what results were obtained for each term. Combining terms prematurely can result in missing important citations.