Clinical and biologic observations of demineralized freeze-dried bone allografts in augmentation procedures around dental implants

To evaluate the possibility of regenerating bone around endosseous dental implants, 3t implants were placed into postextraction sockets or other bony defects, and human demineralized freeze-dried cortical bone powder (DFDB) mixed with tetracycline was packed around the exposed parts. Implants were covered with expanded polytetrafluoroethylene (e-PTFE) membranes for 4 to 6 months until abutment connection, unless the membranes were prematurely exposed and had to be removed. Bone biopsies from nonsupporting regenerated bone were taken from some of the patients and examined histologically. Whenever complete coverage was maintained throughout the healing period (4 to 6 months), complete bone regeneration resulted. Early membrane removal mainly resulted in partial bone regeneration. Histologically, regenerated bone consisted of particles of devitalized bone in contact with newly formed woven or lamellar bone with some connective tissue around them. Osteogenic activity was even present 1 year post-grafting. Thus, DFDB is capable of promoting bone formation around dental implants if complete flap coverage and the membrane presence can be maintained throughout the healing phase.