Influence of decortication of the donor bone on guided bone augmentation -An experimental study in the rabbit skull bone

The aim of the present study was to evaluate if early access to the endoste al bone compartment by removal of the outer cortical bone plate will enhanc e bone augmentation in a secluded space. Two titanium cylinders were placed on the skull of each of 8 rabbits. Each cylinder was placed into a circula r slit, secured to the skull bone via two mini-screws and supplied with a t itanium lid. On the test side, the outer plate of the cortical bone, demarc ated by the slit, was removed. The subsequent bleeding resulted in blood fi ll of the cylinders to various degrees. On the control side, the cortical b one plate was left intact and no bleeding was observed at the time of the p lacement of the titanium lids. After 3 months, the animals were sacrificed to obtain histology and histomorphometry. No differences in the total amoun t of augmented bone tissue, in relation to the total experimental area (75. 5%+/-10.9% at the test sites and 71.2%+/-13.5% at the control sites) or of the augmented mineralized bone tissue in relation to the total amount of au gmented bone tissue, was revealed (17.8%+/-3.0% and 16.0%+/-4.9% respective ly). There was no difference in the morphological appearance of the augment ed bone between test and control sites and there were no obvious similariti es in the appearance between the newly formed bone tissue and the donor bon e. The augmented bone consisted of slender bone trabeculae, distributed in abundant marrow spaces. A conspicuous finding was that the bone trabeculae tended to climb along the inner walls of the titanium cylinder. It is concl uded that decortication of the calvarial bone in the rabbit does not result in more bone formation beyond the skeletal envelope after a healing period of 3 months compared to no removal of the cortical bone plate inside a sec luded experimental area.