Date	Event	Description
12 September 2011	New search has been performed	For the second update, the main changes were as follows: 1. The search for trials was updated to August 2010. 2. Risk of bias was assessed for sequence generation, allocation concealment and blinding of outcome assessors. 3. There were two newly included trials (Frihagen 2007 and Mouzopoulos 2008). 4. Extra reference to the study of Rogmark 2002 added. 5. Extra references and data for two studies added after publication of long term follow‐up results for two studies (Parker 2002; Rogmark 2002). 6.Two newly identified studies (Pathi 1989; Shafee 2007) were excluded. 7. There were no changes to the conclusions of the review.