Ablative laser resurfacing with pulsed carbon dioxide and erbium YAG lasers, when introduced, was considered radical for its day.
It rapidly gained acceptance but diminished in popularity due to undesirable side effects and prolonged recovery times. This led to the development of nonablative devices, which were very safe but produced, at best, modest results.
While ablative laser resurfacing still remains a key component in the armamentarium of laser resurfacing, the development of fractional laser technologies is rapidly gaining acceptance for skin resurfacing for a myriad of dermatologic applications.
Fractional resurfacing employs the concept of "partial" treatment of any given surface area, allowing the preservation of an intact stratum corneum with levels determined by selecting fluence, pulse width and densities. With the treatment of microscopic areas, wound healing will take place via migration of keratinocytes from the surrounding untreated areas. This results in faster wound healing, reduced downtime and a lower complication rate.
So what is the downside? Ablative procedures usually require a single treatment, while fractional resurfacing requires between three to five treatments.
Fractional treatment parameters
The term "fractional resurfacing" is creating some confusion, as true fractional resurfacing employs key parameters while "pseudo-fractional resurfacing" tweaks existing devices and is more marketing than science.
The parameters of a fractional treatment are determined by the following:
The most important factor in true "fractional resurfacing" is that the spot size should be small enough to allow for easy migration from the surrounding untreated areas. How small this should be is probably on the micron level, but the upper limits of what will be acceptable have yet to be determined.
Beware of companies marketing their scanning devices as "fractional" lasers; as simply treating part of the skin does not qualify the device as a fractional device. Moreover, the mid infra-red wavelengths between 1500 nm and 1600 nm are optimal for nonablative fractional resurfacing, as they achieve appropriate depths with optimal absorption of the chromophore. Other wavelengths are either too superficial or have significant interference with other chromophores, making them less desirable to true nonablative fractional resurfacing.
As the technology is fairly new, we are continuing to understand the significance of these parameters. The Fraxel SR750 (Reliant Technologies) is the first true fractional laser and is cleared by the Food and Drug Administration (FDA) for treatment of skin resurfacing of the face and nonface, periorbital rhytides, acne and surgical scars, melasma, pigmented lesions and soft tissue coagulation.
The second generation Fraxel-TM SR1500 laser was introduced in 2006 and refines Fraxel treatments with the ability to deliver higher fluences, wider microthermal zone settings and a more ergonomic handpiece. Fraxel treatments are coined NFR (nonablative fractional resurfacing). The chromophore for the 1550 nm laser is water, with the appropriate depth of penetration to allow for dermal neocollagenesis, with depths up to 1000 microns. Depth is particularly critical for acne scars and rhytides. NFR with Fraxel-TM treatments require an optical tracking blue dye. The mode of resurfacing is with random patterns with surface area coverage varying from 5 percent to 40 percent based on levels of treatment and fluences up to 40 joules/cm2 .