Conduct of multicenter trials to test agents for treatment of periodontitis.

The conduct of multicenter trials to test agents for treatment of periodontitis is conceptually similar to that of single center trials, but the requirement that centers ultimately be combined into a single result places much more stringent requirements on uniformity and control. Multicenter trials should be considered only if numbers of subjects or the ability to generalize to other treatment settings becomes a driving theme. General guidelines for the conduct of studies of this sort are suggested and problems that occur are discussed. Despite formidable difficulties that may occur, multicenter studies provide a convincing demonstration of an agent's therapeutic efficacy for the treatment of periodontitis.