In adults with periodontitis (P) what is the effect of manually flossing (I) compared to using interdental aids (C) on gingivitis scores (O)?
TIP: When constructing a search strategy, it's best to use just the keywords representing the population/problem and intervention, not keywords for the comparison and outcome. Including all will likely retrieve few results.
For example, periodontitis and flossing would be the two concepts to include in your search, not interdental aids and gingivitis scores.