극초단파 이산화탄소 레이저를 이용한 레이저 박피의 피부 조직학적 변화에 대힌 실험적 연구 = AN EXPERIMENTAL STUDY OF THE HISTOLOGICAL CHANGES IN LASER RESURFACING USING THE ULTRAPULSE CO₂LASER

다국어 초록 (Multilingual Abstract)

The purpose of this study was to evaluate the histological changes and depth of vaporization and thermal injury that occur after resurfacing using an ultrapulse CO2 laser on an animal model. It also addresses the appropriate fluence for skin resurfacing using the ultrapulse CO2 laser in clinical cutaneous surgery. The ultrapulse CO2 laser resurfacing of 9 guinea pig skins were investigated. Macroscopic and microscopic observation of the resurfacing sites were evaluated for 3 months. In groups 1,2, and 3 with a radient exposure if 250 mJ at 5 Watt were irradiated with 1,2, and 3 passes respectively. In groups 4,5, and 6,400 mJ at 5 Watt were irradiated with 1,2,and 3 passes respectively. In group 7,8, and 9,500 mJ at 5 Watt were irradiated with 1,2, and 3 passes respectively. the depth of resurfacing and thermal damage were investigated on the first day of application. The tissue reepithelialization and middermal wound healing were observed after 3 days, 1 week, 2 weeks, 4 weeks, 6 weeks, and 3 months, respectively. The results are as follows :
1. Macroscopically, unscarred skin reepithelialization was seen within 2-3 weeks. Reepithelialization occurred sequentially, beinning at group 1 and ending at group 9.
2. The mean vaporization depths were 13,16, and 22 μm in groups 1,2 and 3, respectively. In groups 4,5 and 6, the mean vaporization depths were 25,31, and 42 μm, respectively. In groups 7,8, and 9, the mean vaporization depths were 32,53, and 83 μm respectively.
3. The depth of thermal damage was approximately 50 μm in group 1, 70 μm in group 4, and 80 μm in group 7; namely it was proportioned to fluence.
4. In wound healing using laser resurfacing , reepithelialization was thicker than the control in groups 1, 2, 3, 4, 5, and 7 on the third day of application. In the other groups, reepithelialization was thinner than the control. All the groups lacked a granular therefore, showing immature appearance. After the first 2 weeks, reepithelialization of the wound using laser resurfacing resulted in the multiplying of epidermal layers. After 1 weeks, all the groups, except group 9, showed epidermal hyperplasia with a focal granular layer. After the second week, the epidermal layer was thicker than the first week. Also , the epidermis showed mature appearance including a granular layer. After the fourth week, the epidermal thickness decreased. In the sixth week, the epidermal thickness was 20-30% thicker and flatter than the control.
5. Capillary congestion and decreased dermal integuments and relative transversely arranged collagen fibers within the papillary dermis were observed at the end of the first week. By the end of 2 weeks, more marked capillary congestion and more transverse arrangement of collagen fibers were observed. By the end of 4 weeks, the restored papillary dermal collagen showed a relative compact configuration and a greater cellularity. By the end of 3 months, these transversely collagen fibers continued their transverse arrangement.
In conclusion, the ultrapulse CO2 laser in an effective and safe modality for the resurfacing of aging skin and treatment of cutaneous lesions.