Comparison of carbon dioxide laser, erbium : YAG laser, dermabrasion, and dermatome - A study of thermal damage, wound contraction, and wound healingin a live pig model: Implications for skin resurfacing

Background: Advances in laser technology allow for precise tissue removal a nd minimal thermal damage. However, mechanisms for cosmetic improvement hav e not been determined. Investigators have suggested that ablation, collagen shrinkage, and new collagen deposition all contribute to the clinical outc ome. Objective: In a live farm pig, we examined gross and microscopic effects of thermal and mechanical ablation devices to characterize immediate and long -term mechanisms in skin rejuvenation. Methods: Two CO2 lasers, an erbium:YAG laser, a dermabrader, and a dermatom e were used to treat Bank skin in a farm pig. There were 14 different treat ment groups based on device type and working parameters. One to five sites were treated for each group. Wound surface areas were measured before treat ment, immediately after treatment, and 7, 17, 23, 30, and 60 days thereafte r. Biopsies were performed immediately after irradiation and 2, 7, 17, and 60 days after treatment. Results: For the CO2 laser-induced wounds, surface area measurements showed that immediate and final wound contraction tended to increase with initial residual thermal damage (RTD) for a range of values, above which immediate contraction remained relatively constant. Although there nas no immediate wound contraction with mechanical ablation devices, long-term wound contrac tion in the dermatome and dermabrasion sites increased with depth of ablati on. The erbium:YAG laser sites healed in a manner similar to that of mechan ically induced wounds. Wound contraction profiles over time were dependent on depth of RTD and depth of ablation. Sixty days postoperatively, histolog ic examination showed varying degrees of fibroplasia. Overall, there was gr eater compaction and horizontal orientation of collagen fibers in those wou nds with more than 70 mu m of dermal RTD. Grossly, all wounds were similar after 60 days, with the exception of the deep dermabrasion sites, at which clinical scarring was observed. Conclusion: Our results show that CO2 laser resurfacing produces short- and long-term wound contraction that is greater than that induced by purely ab lative methods for the same total depth of injury. The erbium laser produce d Round contraction profiles similar to these produced by mechanical woundi ng. The data suggest that initial collagen contraction and thermal damage m odulate wound healing.