HEALING OF FREE GINGIVAL GRAFTS WITH AND WITHOUT PERIOSTEUM .2. AUTORADIOGRAPHIC EVALUATION

Free gingival grafts were placed on periosteum and on bone in five adult male Rhesus monkeys. Three of the monkeys received an intravenous injection of tritiated thymidine 1 hour prior to sacrifice. After processing, radioautographs covering postoperative periods from 1 hour to 45 days were obtained. Labeled cell counts were obtained in five areas: bed, grafted connective tissue, grafted epithelium, surrounding connective tissue, and surrounding epithelium. A total of 160 slides were evaluated, 80 on periosteum and 80 on bone. Diagrams were made comparing the mean labeled cell values for each individual area after both procedures. A mean total activity was also determined and analyzed statistically. Results showed that the total rate of healing was initially similar whether grafts were placed on bone or on periosteum, as indicated by the total cell labeling counts. However, after 14 days, cell proliferation became significantly higher with grafts on bone. The presence of the periosteum warranted early proliferation at the level of the bed, since with grafts on bone no activity was seen there until 7 days. Similar rates of proliferation were seen in the surrounding areas, including both connective tissue and epithelium, with increased activity confined to the 1st week. The epithelial coverage of the graft was restored by migrating epithelial cells from the surrounding areas, and also by proliferation of remnants of deep rete pegs in the grafted tissue. These remnants showed labeling at 2 days. Within the limits of this study the following conclusions can be drawn: The total rate of cell proliferation after a free gingival graft procedure is similar whether on periosteum or on bone. Proliferation from the surrounding tissues will be sufficient to warrant the success of the graft. The presence of the periosteum in the bed will provide a source for initial repair at the interface. Remnants from deep rete pegs in the graft will contribute to its reepithelialization. Delayed remodeling is expected when grafts are placed on bone. This affects mainly the newly formed periosteum.