A comparative study of epithelialization of subcutaneous fascial flaps and muscle-only flaps in the oral cavity. A rabbit model.

Epithelialization of subcutaneous fascial flaps and muscle-only flaps used for reconstruction of the oral mucosa were studied in a rabbit model. Angiography was performed to help to design a subcutaneous cervical fascial flap and a cleidomastoid muscle-only flap. These flaps were transferred into a mucoperiosteal defect on the mandibular alveolus. The flaps were gradually infiltrated by acute inflammatory cells from the periphery and then replaced by granulation tissue originating from the oral mucosa. The epithelialization was by secondary intention. An epithelial tongue from the surrounding epithelium migrated onto the granulating flaps with eventual coverage after three weeks. After two months, the muscle-only flap was covered by a poorly organized epithelium, different from the highly uniform epithelium in the fascial flap. The granulation tissue which replaced the muscle-only flap matured to fibrous tissue, associated with severe contraction. This was characterized by dense regular collagen fibers, no elastic fibers, and few capillaries, while the fibrous tissue which replaced the fascial flap was characterized by random collagen and elastic fiber morphology and numerous dilated blood vessels, and was associated with mild contraction. This experiment supports the view that the different extracellular matrices of these flaps may play a role in epithelial configuration and contraction.