Although carbon dioxide laser resurfacing machine has become increasingly popular, concerns have been raised about this laser's thermally induced effects on the skin. Such thermal damage may lead to delays in healing, prolongation in posttreatment erythema, and an increased risk of postinflammatory pigmentary changes. The erbium: YAG laser, with its 2940 nm wavelength at the peak of water absorption, leads to less thermal damage in laser-treated skin. This study describes the clinical results in 100 patients with class I and II facial rhytids treated with the erbium: YAG laser.

Laser skin resurfacing involves an intentional controlled skin injury with the dual aims of reepithelialization and collagen remodeling. This process leads to improved skin texture and a more youthful appearance. Char-free pulsed CO₂ lasers are effective in promoting skin rejuvenation. Mechanisms of action have included epidermal ablation, dermal damage with collagen remodeling, and thermal contraction of treated collagen. CO₂ laser resurfacing leads to a dramatic improvement in rhytids classified as class I, II, and III. The best results have been seen in white skin. Reepithelialization usually occurs in 1 to 3 weeks. Unfortunately, the risk of postinflammatory hyperpigmentation has limited the role of this laser in the treatment of darker skin types (Fitzpatrick skin types IV and higher). In addition, delayed hypopigmentation and the increased risk of scarring of treated nonfacial skin have tempered the use of CO₂ lasers. 

The erbium: YAG (Er:YAG) laser is a new addition to the armamentarium of skin resurfacing lasers. This laser, with a wavelength of 2940 nm, produces laser irradiation in the near infrared portion of the electromagnetic spectrum. This wavelength corresponds to the main peak of water absorption. The water absorption coefficient is 12,800/cm, compared with the CO₂ laser water absorption coefficient at 800/cm. The Er:YAG laser can remove as little as 1 mm of skin with a single laser impact; the ablation threshold is only 1.6 J/cm².

The Er:YAG laser releases pulses of 250 to 350 us duration. Typically, this laser ablates approximately 5 to 35 mm of skin/impact with minimal thermal damage. 

The zone of Er:YAG laser thermal necrosis is usually less than 30 to 50 mm.  This is in contrast to an initial depth of CO₂ laser-induced thermal injury of approximately 75 to 150 mm.  It has been suggested that these attributes lead to the observed faster wound healing and shorter duration of erythema after Er:YAG laser resurfacing.