HEALING OF FREE GINGIVAL GRAFTS WITH AND WITHOUT PERIOSTEUM .1. HISTOLOGIC EVALUATION

The healing of free gingival grafts placed on periosteum or on denuded bone was evaluated histologically in five adult male Rhesus monkeys. Forty gingival grafts were performed, covering observation periods from 1 hour to 72 days. When grafts were placed on bone there was an initial delay in healing. However, by 28 days the rate of healing for grafts placed on bone was similar to that for grafts on periosteum. The periosteal bed seemed to favor a better initial adaptation at the level of the interface, which might have accounted for a better nourishment of the grafted tissue. As a consequence, grafts on bone showed initially more significant degenerative changes involving the superficial connective tissue, and a delay in the starting of the epithelial migration. The epithelial coverage was restored in 7 days when the grafts were on periosteum and in 14 days when they were placed on bone. Keratinization was found in both instances after 28 days. The bone was undisturbed when the grafts were on periosteum. However, when grafts were placed on bone, the bone showed initially empty lacunae followed by bone resorption and repair. Specific stain showed the persistence of elastic fibers in the connective tissue when the grafts were on periosteum. This was not observed when they were placed on bone. Within the limits of this study the following conclusions can be drawn: 1. The maintenance of the periosteum on the recipient site does not affect the success of a free gingival graft. 2. The initial healing is delayed when grafts are placed on bone. 3. After 28 days, there is no difference in the rate of healing whether a graft is placed on bone or on periosteum. 4. Grafts on bone produce superficial bone remodeling. 5. Elastic fibers may persist when grafts are placed on periosteum.