A comparison of scar revision with the free electron and carbon dioxide resurfacing lasers

Laser scar revision was studied to measure the effects of targeting extracellular matrix protein versus tissue water on scar revision. We compared the free electron laser used at 7.7 mum (the amide III protein absorption band) to the carbon dioxide (CO2) laser and dermabrasion. Nude mice (n = 40) that had rejected skin grafts on their dorsal surface and developed mature scars were used as a model for scar revision. One-half of each scar was revised with either the free electron laser at 7.7 mum (32 to 38 mJ, nonoverlapping pulses delivered with a computerized adjustable pattern generator at 30 Hz, and two to three passes), a 100-mu sec CO2 resurfacing laser (500 mJ, 5.0 Hz, and two to five passes), or dermabrasion. The untreated portion of each scar served as an internal control. Evaluation was by measurement of the clinical size of the scar using photography with quantitative computer image analysis to compare the data and histology to evaluate the quality and depth of the scars. The free electron laser at 7.7 mum was significantly better than the CO2 laser and dermabrasion for scar size reduction (p < 0.046 and p < 0.018). The CO2 laser and a highly skilled dermabrader were not statistically significantly different (p < 0.44). The result seen with less skilled dermabraders was significantly worse than all other methods (p < 0.009). The free electron laser at 7.7 mum, which is preferentially absorbed by the proteins of the extracellular matrix, provided better scar reduction than the CO2 resurfacing laser and dermabrasion. Dermabrasion by a skilled operator resulted in improvement similar to the results obtained with the CO2 resurfacing laser, but less skilled operators had significantly poorer results.