Date	Event	Description
14 September 2011	New citation required but conclusions have not changed	New author added to the review team.
12 August 2011	New search has been performed	First update new search, three new trials included (Abouzari 2009; Celik 2007; Nascimento 1991); as a result of further assessment one trial which was previously excluded has been included in this update (Ilankovan 1992), and one trial which was previously included has now been excluded (Ko 1992). The conclusions of this update remain unchanged.
21 September 2010	New search has been performed	Converted to new review format
21 April 2006	New citation required and conclusions have changed	Substantive amendment