Fractional resurfacing
Introduction
There are various laser procedures for skin remodeling. There is, however, an increasing demand for an effective treatment with minimal side effects and downtime.
Ablative skin resurfacing lasers such as carbon dioxide and erbium:YAG (Er:YAG)1., 2., 3., 4., 5., 6., 7., 8., 9. (Fig. 1D) remove the epidermis and cause residual superficial thermal damage within the dermis. Carbon dioxide laser is the most effective laser treatment of signs of photoaging such as wrinkles and dyschromia, and usually requires a single treatment. It is, however, associated with significant side effects and downtime. Side effects include pain, burning, edema, oozing, crusting, infection, prolonged erythema, pigmentary alterations, and scarring.
Er:YAG laser is associated with faster healing time and fewer side effects. It is less effective than carbon dioxide laser, however, because of its superficial absorption depth, decreased ablation, and less residual thermal dermal damage.
To reduce the side effects associated with ablative skin resurfacing, nonablative lasers (Fig. 1A) were introduced. Nonablative lasers penetrate the skin deeper and selectively heat up and damage the dermal tissue while sparing the epidermis. Epidermal protection is achieved by coupling the nonablative laser with a cooling device. Nonablative dermal remodeling is characterized by minimal side effects and downtime. Compared to ablative skin resurfacing, however, it has limited efficacy and requires multiple treatments.10., 11., 12.
Fractional resurfacing (FR) is a newer concept of skin rejuvenation that produces a unique thermal damage pattern.13., 14. Fractional resurfacing produces discrete columns of thermal damage at specific depths (Fig. 1B), referred to as microthermal treatment zones (MTZs). It characteristically spares the tissue surrounding each column resulting in rapid epidermal regeneration due to fast migration of the surrounding viable keratinocytes present at the wound edges. Recently, the concept of ablative fractional resurfacing (AFR) (Fig. 1C) has been introduced using ablative lasers such as a focused carbon dioxide laser.15., 16.
Section snippets
Nonablative fractional resurfacing
The first and the most extensively studied nonablative fractional resurfacing (NAFR) laser is the Fraxel SR laser (Reliant Technologies, Palo Alto, Calif). The light source for the Fraxel laser system is an erbium-doped fiber laser lasing at 1550 nm. Most of the data presented in this review are obtained from studies with the Fraxel laser or the prototype device.
Other nonablative fractional devices that are currently being studied include Lux 1540 nm laser (Palomar Medical Technologies,
Perioperative evaluation
The ideal candidate is a fair skin patient (skin types I-III). Still, NAFR is safer in darker skin types than ablative resurfacing. It is also safer to use off the face, including neck, trunk, and extremities.
A complete medical history should include history of herpes labialis, keloid or hypertrophic scar formation, postinflammatory hyperpigmentation (PIH), Accutane intake, topical retinoid use, and lidocaine allergy. All of these considerations are relevant to a determination of who is an
Predictable side effects
Predictable side effects are those effects that occur consistently with every treatment and are usually mild, a characteristic feature of the fractional laser treatment. They include the following: (1) postoperative discomfort, which is generally mild and transient; (2) sunburn sensation for approximately 1 hour postoperatively; (3) sunburnlike erythema that may persist for 3 to 7 days; (4) edema, which is generally minimal, and usually resolves in 2 to 3 days; (5) bronzing, which is usually
Clinical applications
The choice of laser parameters varies depending on the clinical target. For epidermal processes such as lentigenes, dyschromia, or melasma, lower fluences (6-10 mJ) are usually adequate with a density setting of 250 MTZs/cm2 to a total density of 2000 to 3000 MTZs/cm2 (8-12 passes). For deeper processes such as wrinkles or scarring, higher fluences (10-20 mJ) are usually needed. It is recommended to use the lower density setting of 125 MTZs/cm2 with higher energies to avoid excess bulk tissue
Ablative fractional resurfacing
The latest concept in dermal remodeling is AFR15., 16. (Fig. 1C) using ablative lasers such as a focused carbon dioxide laser or Er:YAG laser. This new concept for dermal remodeling combines the theories of ablative resurfacing and nonablative FR (Fig. 1). A focused carbon dioxide laser was used on postmortem human skin with a focused 0.2-mm handpiece in combination with x-y micrometer stage with well-defined distances of 1 mm. Single pulses of 100 to 500 mJ with constant pulse duration of 1 ms
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