Epithelialization process of free fascial flaps used in reconstruction of oral cavity mucosa defects in dogs.

Bare free fascial flaps are increasingly used for restoration of soft-tissue defects of the oral cavity because they provide thin, foldable tissues with high epithelialization capacity to preserve local anatomy as well as chewing, phonation, and deglutition. However, there are unanswered questions regarding the epithelialization process and other histopathologic changes occurring after transfer of these flaps into the oral cavity. To investigate these changes thoroughly, an experimental study was conducted in the dog model. Bare dorsal thoracic fascia was used as the free flap model. Ten adult dogs were used in this experiment. Oral mucosa defects measuring 6 x 5 cm were created. Free dorsal thoracic fascia flaps were harvested. The vascular pedicle of the fascia flap was anastomosed with the superior thyroidal artery and external jugular vein. Then, the flaps were transferred into the mucosa defects. The dogs were divided into groups, each composed of two animals. At 7, 14, 21, 30, and 60 days postoperatively, general anesthesia was administered to the groups 1, 2, 3, 4, and 5, respectively. First, clinical assessment was performed; then specimens were obtained. Initially, the flaps were gradually infiltrated by acute inflammatory cells coming from the circulation and then replaced by granulation tissue. Epithelial cells deriving from wound margins migrated onto the granulating flaps with eventual coverage of highly organized epithelium after 4 weeks, and the fascia flap could not be differentiated from the native mucosa. The flaps were replaced by normally maturated fibrous tissue containing regular collagen fibers, instead of atypical scar tissue. Wound contraction was calculated as 18 percent at postoperative day 60. It was detected that bare free fascia flaps used in the repair of mucosa defects act as a scaffold and complete epithelialization from surrounding margins. They can be accepted as the main surgical option for the reconstruction of oral cavity mucosa defects.