THE IMPORTANCE OF THE DURA IN CRANIOFACIAL SURGERY

The hypothesis of this study is that craniofacial procedures that rely on devascularization of cranial bone are successful largely because o f the unique environment that the dura offers. This hypothesis was tes ted by sequentially labeling animals with tetracycline and studying th e healing of cranial bone grafts when replaced immediately and when su bjected to room air exposure for 90 minutes and contrasting healing in mature and immature animals. Bilateral parietal bone flaps were harve sted from guinea pigs. On one side, the bone was replaced as a control , and on the other side, the dura was resected prior to replacing the bone flap. The animals were divided into four groups of five animals e ach. The first and second groups were immature animals (3 to 4 weeks o f age), and the third and fourth groups were mature animals (4 to 6 mo nths of age). In the first and third groups, the bone flaps were repla ced immediately, and in the second and fourth groups, the bone flaps w ere exposed to room air for 90 minutes, since this has been shown to d estroy surface osteocytes and simulates extreme exposure conditions th at could occur in clinical situations. Sequential marking with tetracy cline was performed to study the mineralization rate and overall matri x formation. Significantly decreased mineralization rates occurred in bone flaps not in contact with dura. In those bone flaps exposed to ro om air for 90 minutes, healing occurred only on the side where dura wa s present. The clinical implications of the importance of the dura in craniofacial procedures are discussed.