Table 1 summarizes the results of the searches for studies involving PCCs. It shows (a)
the number of studies initially identified by the search, (b) the number of additional studies
identified through other sources, (c) the number of these studies that either of 2 reviewers
targeted for detailed review, and (d) the number found to address the key question irrespective of
the research design employed by the study. Table 2 summarizes the sources of collateral
evidence for effectiveness from the dental literature for 3 key questions.