Pulsed dye laser treatment with different onset times for new surgical scars: a single-blind randomized controlled trial

Abstract

In humans, regeneration of wounds is limited and the wound repair process leads to a nonfunctioning mass of fibrotic tissue known as a scar, which can be more or less visible [1]. The final appearance of a surgical incision is an important concern for patients and physicians. Scarring can cause discomfort and psychological stress for patients. Surgical scars can be flat, hypertrophic or atrophic. The etiology and mechanism of scarring are not fully understood. Scars are thought to be difficult to treat and almost impossible to prevent. Several nonsurgical (pressure garments, topical and systemic corticosteroids, silicone gel sheeting, 5-fluorouracil, radiotherapy, interferon, bleomycin, topical retinoic acid, colchicine, D-penicillamine) and surgical interventions (laser, cryosurgery, skin grafting, scar revision, dermatography) have been investigated for the treatment of scars [2–6]. Laser treatment may provide an alternative to the long list of current treatment options. Different laser systems have been used to prevent or treat scars. The argon laser was introduced in 1978 [7]. Abergel et al. showed the effectiveness of the 1,064 nm Nd:YAG laser in the treatment of scars [8]. Castro et al. [9] found that the effect of the Nd:YAG laser (at an energy level of 1.7×10 J/cm) could be due to selective inhibition of collagen production with no effect on DNA synthesis or cell viability. The diode laser has also been used for the treatment of scars. A preliminary study has suggested that treatment with the diode at 810 nm in the early phases can change the physiology of wound healing significantly, and thus prevent scar formation [10]. In 1993, Alster reported that the flashlamp pulsed dye laser (PDL) at 585 nm significantly improves erythematous and hypertrophic scars [11]. PDL is currently the laser of choice for the treatment of scars. The exact mechanism by which PDL exerts antiscarring effect remains unclear. The majority of the lasers including PDL emit light energy that is absorbed by hemoglobin, generating heat and resulting in damage to the microvasculature [12]. It has been reported that the 585-nm PDL can decrease fibroblast proliferation and collagen type III deposition [13]. McCraw et al. were the first to describe the use of laser therapy of postsurgical scars. In an uncontrolled study they found that early laser therapy was safe and effective [14]. Nouri et al. in a controlled study found that the 585-nm PDL on the day of suture removal is effective and safe in the treatment of fresh surgical scars [15]. This finding was confirmed again in another study using a cryogen-cooled 595-nm PDL laser [16]. On the other hand it seems that one single pass of the PDL on the day of suture removal does not improve the appearance of surgical scars and more than one pass is recommended [17]. In a trial comparing the 585-nm with the 595-nm PDL, Nouri et al. found that 585 nm was the preferred wavelength, as it markedly normalized the height, vascularity and elasticity of scars [18]. Additionally, Nouri et al. reported that both shortand long-pulse PDL started on the day of suture removal effectively and safely improve the quality and cosmetic appearance of surgical scars [19]. Although laser treatment on the day of suture Clinical trial registration number: NCT00506363 P. Davari : F. Gorouhi : P. Hashemi : F. Behnia : M. Nasiri-Kashani :A. Firooz (*) Center for Research and Training in Skin Diseases and Leprosy, Tehran University of Medical Sciences, 415 Taleghani Ave, Tehran 14166, Iran e-mail: firozali@sina.tums.ac.ir