The influence of cortical perforations and of space filling with peripheral blood on the kinetics of guided bone generation - A comparative histometric study in the rat

The aim of the present study was to evaluate the influence of cortical perforations and of peripheral blood addition in guided bone generation beyond the skeletal envelope in rats. A total of 30 isogenic adult rats were divided into 3 equal groups. In each rat, two hollow parallelipipedic titanium chambers were placed bilaterally on the calvaria after a periosteal skin flap was raised. While on the right sides (controls) the osseous surface was left intact and the chambers were empty, the cortical bone under the left-side chambers (test sites) was perforated with nine 0.8 mm-diameter holes (group I), or left intact but with the chambers filled with a clot of peripheral blood (group II). In group III, both procedures were combined in the test sites. The healing was assessed at 4, 8 and 16 weeks after surgery by histologic and computer-assisted histometric analysis. The results demonstrated a substantial augmentation of on average 141% (SD 18) of the skull's thickness after 16 weeks in the controls, indicating that a predictable bone formation can be achieved beneath completely occlusive barriers over a non-injured cortical layer. In all test groups, a significantly larger bone augmentation was observed after 16 weeks compared to the control sites: 172.8% (SD 41.7) in group I (P<0.05), 172.0% (SD 18.4) in group II (P<0.05) and 221.5% (SD 42.3) in group III (P<0.001), demonstrating that stimulating blood supply and bone forming cells access by cortical perforations and/or blood clot addition enhances de novo bone formation in this experimental model.