Microscopic evaluation of the healing and revascularization of free gingival grafts

The objective of this study was to observe the microscopic appearance of the healing and revascularization of free gingival grafts when placed over periosteum. Seven rhesus monkeys were used to provide observation periods of 0, 2, 4, 5, 7, 8, 11, 14, 17, 21, 28, and 42 days following surgery. After dissection and excision of a split flap in the anterior region to prepare the graft bed, a mucoperiosteal graft of attached gingiva from the buccal of the premolar area was sutured in place. The animals were injected with carbon serum just before sacrifice and after preparation the histologic and cleared specimens were studied under the microscope. The results indicate that the healing and revascularization of free gingival graft and skin grafts are similar. Cellular nutrition was maintained for the first few days by a “plasmatic” circulation. Revascularization occured initially by anastomoses between vessels of the graft bed and pre‐existing vessels in the graft and later by capillary budding which penetrated the graft. Carbon serum was present in the vessels of the graft at four days. There was increasing vascular density up to seven days followed by a gradual reduction and return to a normal vascular pattern after 14 days. The graft was initially separated from the bed by a thin layer of fibrinous exudate. Fibroblasts proliferated into the area and a firm fibrous union to the periosteum was apparent between 7–11 days. Initial disintegration of most of the graft epithelium ccured. Re‐epithelialization resulted from migration of new epithelium from adjacent gingiva and from surviving basal cells of the graft epithelium. The epithelium had a relatively normal appearance by 14 days although new keratinization was not apparent for 28 days. The connective tissue disintegrated in portion of some of the graft and was replaced by granulation tissue which delayed healing.