Effect of monopolar radiofrequency treatment over soft-tissue fillers in an animal model: Part 2

Background and Objective Monopolar radiofrequency (RF) treatment is used by physicians to heat skin and promote tissue tightening and contouring. Cosmetic fillers are used to soften deep facial lines and wrinkles. Patients who have had dermal fillers implanted may also benefit from or are candidates for monopolar RF skin tightening. This study examined the effect of RF treatment on various dermal filler substances. This is the second part of a two-part study. Study Design/Materials and Methods A juvenile farm pig was injected with dermal fillers including cross-linked human collagen (Cosmoplast™), polylactic acid (PLA) (Sculptra™), liquid injectable silicone (Silikon™ 1000), calcium hydroxylapatite (CaHA) (Radiesse™), and hyaluronic acid (Restylane®). Skin injected with dermal fillers was RF-treated using a 1.5-cm2 treatment tip and treatment levels typically used in the clinical setting. Fillers were examined histologically 5 days, 2 weeks, or 1 month after treatment. Histological specimens were scored for inflammatory response, foreign body response, and fibrosis in order to assess the effect of treatment on early filler processes, such as inflammation and encapsulation. Results Each filler substance produced a characteristic inflammatory response. No immediate thermal effect of RF treatment was observed histologically. RF treatment resulted in statistically significant increases in the inflammatory, foreign body, and fibrotic responses associated with the filler substances. Conclusions Monopolar RF treatment levels that are typically used in the clinical setting were employed in this animal study. RF treatment resulted in measurable and statistically significant histological changes associated with the various filler materials. Additional clinical and histological studies are required to determine the optimal timing of monopolar RF treatment and filler placement for maximal potential aesthetic outcome. Lasers Surg. Med. 38:211–217, 2006. © 2006 Wiley-Liss, Inc.