Introduced recently to the Aesthetic market is the concept of "sublative" fractional resurfacing (Syneron, Candela), which uses radiofrequency to partially ablate and coagulate tissue. Though cleared by the Food and Drug Administration in 2009, this new technology received its clearance for fine lines and wrinkles in July 2010.
Sublative fractional resurfacing differs from traditional fractional resurfacing in that it does not use laser or light technology. Radiofrequency delivers non-specific heat to its target tissues, which can result in collagen production and even tightening at certain temperatures.
Delivering radiofrequency energy in a fractional manner allows for the benefits of traditional laser fractional resurfacing, including rapid healing rates and little downtime. This new method of using radiofrequency in a "fractional" manner may offer another possible therapy for darker skin types.
"Sublative" resurfacing is a modified form of bipolar radiofrequency. The radiofrequency is delivered to the skin via tiny electrodes or pins placed onto the surface of the skin. Radiofrequency travels between the tiny electrodes and creates microscopic wounds with sparing of tissue between the treated sites.
The device currently on the market (eMatrix, Syneron) comes equipped with two handpieces, which predetermine the density of the treatment. The lower-density handpiece has 64 electrodes and covers approximately 5 percent of the epidermal surface (Traditional fractional resurfacing generally treats an epidermal surface area greater than 5 percent). This relative sparing of the epidermis with fractional radiofrequency may allow for safer and easier treatment of darker skin types.
After passing the epidermis, the energy of radiofrequency fans out to deliver more heat selectively to the dermal tissues. There is more thermal damage to the dermis than the epidermis, with a pyramid-shaped pattern of coagulation seen on histology.
Selective dermal heating, as opposed to epidermal heating, may be beneficial in treatment of dermal disorders such as scarring, rhytids, striae, laxity and textural abnormalities. Pigmentation, which is mostly epidermal, is not likely to respond well to a treatment with only 5 percent epidermal coverage. The higher-density eMatrix tip offers 12.5 percent epidermal coverage.
Downtime with the low-density tip is minimal, with slight bronzing for a few days. The downtime is certainly less than that seen with ablative procedures and probably equal to that seen with the nonablative fractional systems.
It would seem that based on the properties of radiofrequency, fractional radiofrequency would be superior to some of the nonablative devices in the category of tightening, but no head-to-head studies have been done.
Though only a 5 percent portion of the epidermis is affected, thanks to deeper dermal heat, both coagulation and subablation occur to a greater extent. The width of the damage is 200 microns wide at the epidermis, with a depth of penetration up to 350 microns (Hruza G, Taub AF, Collier SL, et al. J Drugs Dermatol. 2009;8(3):259-265. Gold MH, Heath AD, Biron JA, et al. J Drugs Dermatol. 2009;8(3)Suppl).
As with all bipolar radiofrequency devices, the depth is related to the distance between the electrodes. Hence, the lower-density handpiece (with electrodes placed farther apart) shows a higher depth penetration per energy level. Typically, we relate density with the aggressiveness of the treatment. With fractional radiofrequency, these parameters are separate, with the low-density handpiece delivering deeper heat per setting than the high-density handpiece.