Direct and indirect bone-implant contact. a) Direct bone-implant contact: after 28 days significantly less direct contact in the BMP-2 plasmid group. After 56 days the results were comparable in all groups. b) Indirect bone-implant contact. Also, significantly less in the BMP-2 plasmid group after 28 days. After 56 days, again comparable results of all groups. *a p = 0.02 *b p = 0.001. The boxes show the 25th and 75th percentile and the band in the box is the 50th percentile (the median). The whiskers represent the minimum and maximum of all the data.