Objective  To evaluate the ablative effects of a noval ablative erbium-doped yttrium scandium gallium garnet (Er:YSGG) 2790-nm laser treatment at different depths of the epidermis and dermis tissue.

  Methods  Freshly isolated human skin specimens were obtained from surgically resected face, neck, chest, and upper limb flexor side tissues in 16 patients. The specimens were irradiated with Er:YSGG 2790-nm laser, with a focused spot diameter of 300 μm, an energy of 60-160 mJ, and a scanning area of 10 mm × 10 mm. Microarray mode was established in the skin in vitro. The depth and width of the damage were assessed by HE staining. The therapeutic effectiveness of different pulse energies on different skin tissues were evaluated.

  Results  After the irradiation of Er:YSGG 2790-nm laser, ablative fractional heat damage microarrays formed in the human skin in vitro. Different depths of skin (99-456 μm), including the epidermis, superficial dermis, and deep dermis, were selectively reached when the laser was applied at different pulse energies. The cavities were separated for 294-405 μm, and the inner coking walls of cavity ranged 22-77 μm.

  Conclusions  The no-val ablative Er:YSGG 2790-nm laser, when applied in fractional operations, can create thermal reaction in different body tissues. Treatment with different pulse energies, the microarray mode can be formed in the epidermis and dermis layers of different depths.