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

Lookup NU author(s): Professor Giles McCrackenORCiD, Dr Nick Steen, Professor Philip Preshaw, Lynne Heasman, Fiona Stacey, Professor Peter Heasman


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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. © Blackwell Munksgaard, 2005.

Publication metadata

Author(s): McCracken GI, Steen N, Preshaw PM, Heasman L, Stacey F, Heasman PA

Publication type: Article

Publication status: Published

Journal: Journal of Clinical Periodontology

Year: 2005

Volume: 32

Issue: 11

Pages: 1157-1162

Print publication date: 01/11/2005

ISSN (print): 0303-6979

ISSN (electronic): 1600-051X

Publisher: Wiley-Blackwell


DOI: 10.1111/j.1600-051X.2005.00843.x

PubMed id: 16212577


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