Date	Event	Description
30 November 2010	Amended	Minor edits to figures to ensure greater clarity.
5 November 2009	Amended	Minor edit.
27 May 2009	New search has been performed	Searches updated February 2009.
27 May 2009	New citation required but conclusions have not changed	Change in review authors. Three new included studies.
20 June 2008	Amended	Converted to new review format.
5 August 2005	New citation required and major changes	Substantive amendment. Changes from the first version: Two additional trials were included, and two previously included studies were excluded, but no significant changes in the results and conclusions occurred. Numerous pending and new trials were excluded. Quality assessment was slightly simplified. Data from split‐mouth trials were entered in the MetaView. Heterogeneity is now also assessed by I2. One additional post hoc subgroup analysis evaluating the effects of study design (parallel group versus split‐mouth trials) was evaluated. Several previous post hoc subgroup analyses were excluded. Outcome endpoints are now measured at 1, 5 and 10 years. We have added the dichotomous outcome PAL < 2 mm, and calculated NNT.