With the aim of evaluating the healing process and the metabolic activity of the Delayed Autogenous Bone Graft, two groups of experiments were performed. Adult dogs were used.
In the first group divided in three subgroups according to timing after transplantation of the graft (2, 4, or 8 weeks), histological changes were observed as well as those concerning to the fluorescence of tetracycline deposited in the newly formed bone within the graft. This first experiment was of the autocontrol type, in which the graft obtained from the right tibia was transplanted to the left one and vice versa.
In the second group, divided in two subgroups according to the type of graft used (Delayed or Fresh) the metabolic activity of both grafts was evaluated by means of bone scanning and radioactivity counting in a linear scanner, employing Technetium 99m-pyrophosphate as bone-seeking isotopic compound. This experiment was of the hetero-control type.
The results showed that the Delayed Bone Graft, as used here, re-vascularizes and heals about twice as quick as the Fresh Graft, as seen by the histological and fluorescence examinations. That might be the reason why the first ones reach a status of balance between bone formation and bone resorption much earlier than the second ones, as seen by the scintillographic studies.