Halitosis Research Today is a free monthly online journal that collates and summarizes the latest research about Halitosis, including details on bad breath, oral hygiene, oral bacteria, treatment.

The crossover design to evaluate the efficacy of plaque removal in tooth-brushing studies.

McCracken GI, Steen N, Preshaw PM, Heasman L, Stacey F, Heasman PA

School of Dental Sciences, University of Newcastle upon Tyne, Newcastle upon Tyne, UK. g.i.mccracken@newcastle.ac.uk

OBJECTIVES: To evaluate the crossover clinical trial design to assess plaque removal efficacy of the Sonicare Elite. MATERIAL AND METHODS: A single-cohort, 12-week, two-treatment, single-blind, crossover clinical trial recruited 45 subjects. Plaque was recorded using the modified Quigley and Hein index plaque index (PI). After screening, subjects used the toothbrush for 2 weeks and were reminded to abstain from tooth cleaning 12-18 h prior to appointments. At visit two, subjects were randomized to 2 or 2(1/2) min. brushing time. PIs was recorded pre- and post-brushing. Subjects brushed for the allocated time for a further 2 weeks. At visit 3, PIs were recorded pre- and post-brushing. Two weeks later, at visit 4, the subjects crossed over and the protocol was repeated. RESULTS: There was no evidence of a learning effect within each arm of the crossover. A significant period effect was detected; however, no significant treatment by period effect was found. 2(1/2) min. brushing removed more plaque at full mouth (p=0.037), smooth (p=0.012) and lingual (p=0.002) sites compared with 2 min. CONCLUSION: The crossover design is a valid model for assessing plaque removal efficacy in tooth-brushing studies where no carry-over effect is clinically plausible.

Published 10 October 2005 in J Clin Periodontol, 32(11): 1157-62.
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