THE EFFECTS OF SOFT-TISSUE COVERAGE ON BONE-GRAFT RESORPTION IN THE CRANIOFACIAL REGION

Experiments were performed to study the amount of resorption of endochondral bone grafts in pockets covered by muscle tissue compared to pockets covered by subcutaneous tissue in immature rabbits at 16 weeks post-grafting. In the first group the grafts were used as onlays on the buccal surfaces of the mandible with cover by masseter on one side of the face and subcutaneous tissues on the other. The second experiment was similar but the grafts were fixed semi-rigidly with wiring. In the third the grafts were used as onlays on the cranium with muscle or subcutaneous tissue coverage. The fourth group of bone grafts were implanted into muscle and subcutaneous tissue pockets in the abdominal wall. Bone graft resorption was significantly greater when covered by muscle than by subcutaneous tissue. This effect is probably mediated by movement imparted to the graft by adjacent active muscle, and over-rides any benefits of increased vascularising potential muscle may have. Semi-rigid fixation offered no protection against this effect.