Fig. 2

The surgical procedure. (a) Four circular defects (ø = 8 mm) were created in each calvarium of 12 male white rabbits, and four groups were randomly assigned to the defects. (b) Random assignment of the defects clockwise from top left - control group, collagen membrane only (CM), bone graft with collagen membrane (B-CM) and bone graft only (BG). Specimens were harvested at 2 and 8 weeks postoperatively for histologic and histometric analysis