Adequate exposure of the bone covering the root of the 3rd upper incisor tooth was achieved in 36 young adult mongrel dogs by elevating a mucoperiosteal flap. After removing the vestibular bony wall at this site, a rectangular cavity with 3 bony walls and one dental cement wall was formed. Polyvinyl plastic sponges were implanted in the cavity of 24 animals but not of 12 control animals. Flaps were sutured and operated areas protected with periodontal dressings kept in place by resin splints. Animals were sacrified after 5, 10, 20, 30, 60 and 120 days. Histologic study of maxillae revealed partial neoformation of the surgically removed bony plate. This neoformation occurred in a larger area in the group receiving polyvinyl plastic sponge implant. Healing during osteogenesis occurred more rapidly in the implant group than in control dogs.