"This is the peer reviewed version of the following article: Al-Kattan R, Retzepi M, Calciolari E, Donos N. Microarray gene expression during early healing of GBR-treated calvarial critical size defects. Clin. Oral Impl. Res. 00, 2016, 1–10, which has been published in final form at https://dx.doi.org/10.1111/clr.12949. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving."