Extracellular matrix in healing CO2 laser incision wound.

Extracellular matrix components laminin, Type IV collagen, Type III collagen, and fibronectin, of laser-treated rat tongue mucosa were studied over a healing period of 28 days by using immunohistochemical and electron microscopic techniques. Their distribution and amount in laser wounds was compared with that in scalpel incisions and normal tongue mucosa. Laser treatment caused an extensive destruction of both epithelial and stromal cells but left much of the connective tissue matrix intact. Basement membranes, in particular, appeared to resist laser irradiation. During the study period the laser-induced lesions healed through reparative synthesis of matrix proteins which led to filling of the tissue defects. The regenerative processes with concomitant re-epithelialization took place more slowly in laser-treated than in scalpel incision wounds. The relative resistance of the matrix proteins against laser irradiation and the slow removal and replacement of the residual matrix is suggested to account at least partially for the lack of scarring and contraction frequently observed in laser-treated areas.