Histological and immunohistochemical observations of the wound-healing processes after the use of the Nd:YAG laser in rat skin: Distribution of collagen types IV and VII in connective tissue

The role of the laser in wound-healing processes has been controversial. The aim of this study was to demonstrate alterations of the vascular and basement membrane structural components due to the effect of the laser and also to study the reepithelialization events in the wound surface. Three different full thickness incision wounds were performed in the backs of 15 Net rats with the Nd:YAG laser (20 pulses/see, 1.75 W, group A/30 pulses/sec, 3.0 W, group B) and with the normal scalpel (group C). At 4, 7, 14, 21, and 28 days after surgery, biopsies were removed and histological and immunohistochemical staining procedures were performed. The distribution of collagen types IV and VII in the healed tissues was examined. The data revealed better wound healing in the groups A and C (no significant differences in the two groups) and delayed healing in the high-energy group B with epithelial migration very deep into the connective tissue. The basement membrane components presented in this study were resistant to laser treatment at low energy under conditions in which most cells were destroyed by laser treatment. The findings reveal that laser treatment did not appear to affect organization of collagen types IV and VII if low intensity was used.