As the demand for delaying the aging process increases, skin rejuvenation, especially nonablative cosmetic technology, has become a research hotspot because of its minimal damage, few complications, and favorable effects. Nonablative rejuvenation methods stimulate the body's capacity for regeneration and mainly include radiofrequency (RF) therapy, intense pulsed light therapy, neodymium-doped yttrium aluminum garnet laser therapy, and erbium yttrium aluminum garnet laser therapy, among which, RF is applied widely in clinic.
RF radiation is part of the electromagnetic spectrum, with electromagnetic waves in the range of 3 kHz–300 MHz. RF therapy is a noninvasive technology used for skin rejuvenation, body contouring, and weight reduction. The electric current generated by RF electrodes flows to tissues and produces thermal energy acting on the body. In 2002, the US Food and Drug Administration approved the ThermalCool monopolar RF device (Thermage, Hayward, CA, USA) for smoothing periocular wrinkles.1 The US
Food and Drug Administration subsequently approved RF therapy for treating facial skin in 2006. The applications of RF therapy have since expanded to cosmetic treatment of the cervical, abdominal, and femoral skin.2 With the advantages of few adverse effects and short patient downtime, RF therapy has gained increasing popularity in facial rejuvenation during the last decade.
In this review, relevant English literature published from 2014 to 2020 was retrieved from the PubMed database. The search terms “radiofrequency,” “RF,” “facial rejuvenation,” and “skin tightening” were searched for relevant clinical trials. This review summarizes the potential mechanisms, applications, and types of RF devices currently used in facial rejuvenation. The strengthens and limitations of RF devices are also discussed.
Characteristics of aging skin
Aging of the skin includes intrinsic chronological aging and extrinsic aging, which results in age-related loss of function and esthetics. Photoaging results from prolonged exposure to ultraviolet light and accounts for most aging of the skin. Photoaging is histologically characterized by a thinning epidermis, a decrease in collagen, deposition of abnormal elastic fibers, and vessel ectasia.3 Inflammation and apoptosis are regarded as hallmarks of photoaging. At the molecular level, matrix metalloproteinases increase during the aging process, promoting the degradation of type I and type III collagen fibers in the extracellular matrix.4
The gross appearance of aging skin can be described as follows. Rhytides and striae are prominent clinical signs of aging facial skin. Photodamage and facial expressions can accelerate the formation of fine and coarse wrinkles on the frontal, periocular, and nasolabial areas. With advanced age, increased accumulation of excess epidermal pigmentation causes skin staining such as melasma and age spots. Moreover, the appearance of skin laxity and weakness is a frustrating problem following childbirth and bariatric surgery. Permanent scar formation and post-inflammatory hyperpigmentation (PIH) are secondary to other dermatoses such as acne scars, which can similarly impair facial esthetics. These skin changes make people look much older than they are.
RF devices in facial rejuvenation
The general classification of commercially available RF devices is based on the number of electrodes. The four most commonly used techniques are monopolar, unipolar, bipolar, and multipolar RF and are evaluated in this review. Another application of RF devices is combining them with other physical cosmetic treatment methods. For instance, fractional RF with microneedling can potentiate the penetration and treatment effect without causing unnecessary injury to nearby tissues.5-6 The combination of RF therapy and ultrasound contributes to reduction of the soft layer. The development of these combination therapies has significantly extended the scope of RF applications. Each of the methods mentioned above has unique advantages and applications in cosmetic dermatology.
Monopolar RF therapy
Monopolar RF device was the first approved commercially available RF device for cosmetic purposes, and consists of a generator and a handheld tip. Some of these devices are designed with cooling systems to protect the epidermis from the heating effect produced by RF energy. A grounding pad filled with a conductive electrode paste is placed on the patient's body surface. An electric current generated by the monopolar RF system is delivered through the skin, into the body, and finally to the grounding electrode.5 The dermis is then warmed from 65°Cto75°C, sparing the epidermis.2 The penetration depth of monopolar RF is about 20 to 25 mm, which is deeper than that of bipolar or unipolar RF. Monopolar RF devices have been widely used for smoothing and skin tightening, but adverse events such as pain and burning during treatment tend to be more frequent because of the deep penetration depth. Less frequent adverse reactions are erythema, headache, scarring, edema, fat atrophy, and facial palsy. Animal studies have revealed that inappropriately used monopolar RF energy may also induce ocular effects, mainly cataracts. To avoid these adverse reactions, it is necessary to cover the patient's eyes and set a moderate RF energy level with no immediate overlapping when performing facial monopolar RF treatment.7
A clinical study used monopolar RF device engineered with great power and a self-monitoring circuit for treatment of mid and lower facial rejuvenation with no reported significant adverse events. Each subject underwent four serial treatments at 1-month intervals, and increased collagen was observed at 3 months post-treatment.8
A randomized double-blind study revealed that subjects’ periorbital wrinkles improved after treatment with the monopolar RF device Silk’n SHT (Home Skinovations, Ltd., Richmond Hill, ON, Canada). The analyzed data revealed a mean decrease of 1.49 in the Fitzpatrick score and a significant reduction of rhytides (P < 0.001) in almost all subjects with high satisfaction scores. Additionally, no correlation was found between skin type and wrinkle improvement.9
In 2017, researchers used a 1-MHz monopolar RF device (Cutera, Inc., Brisbane, CA, USA) to treat lower facial tightening and fat reduction for 5 weeks. Most patients reported high satisfaction scores for the skin tightening effects, and the efficacy of the fat reduction was maintained even at the 2-month follow-up. No obvious complications occurred in this study.10
Unipolar RF therapy
A unipolar RF device has a single electrode and emits RF energy in all directions without delivering an electric current. These devices have no grounding pad in contact with the patients’ body. The most marked difference between a unipolar and monopolar RF device is in how they deliver energy. The penetration depth of unipolar RF ranges from 15 to 20 mm.2 Some manufacturers have designed home-use RF devices using a unipolar handpiece, which is safe, convenient, and compliant for users.
A double-blind randomized clinical study evaluated the eyebrow-lifting effect of a home-based novel unipolar RF device (DermaWand; ICTV Brands, Inc., Wayne, PA, USA) in women. Fifty women aged 30–70 years were randomized to receive the active device with 100 kHz or the placebo device on each half of their face, and the eyebrow-to-hairline distance decreased with no adverse therapeutic effects after treatment. This study demonstrated the safety and convenience of a household unipolar RF device in upper facial skin tightening.11
A retrospective study was performed to evaluate the use of a novel unipolar RF handpiece device referred to as Tune Face, which is used skin tightening. After a 3-month follow-up period at a 2-week interval, skin biopsies of the subjects revealed improved skin laxity and an increase in thick collagen bundles in the dermis without pain.12
Bipolar and multipolar RF therapy
With recent developments in RF technology, bipolar and multipolar RF devices have been used in multiple fields. A bipolar RF device comprises two electrodes without a grounding plate. The patient's skin is appropriately positioned between the two electrodes, and a high-frequency electrical current passes through the skin precisely from a handpiece. The penetration depth of bipolar RF is approximately one-half the distance between the two parallel electrodes (about 2–8 mm).13 In contrast, multipolar RF devices use three or more electrodes to deliver thermal energy. One electrode is the positive pole, while the remaining electrodes serve as negative poles. This feature of multipolar RF devices prevents overheating and tissue damage. Adverse events of bipolar RF therapy are limited to mild erythema and swelling and usually resolve a few days after treatment. PIH or hypopigmentation is rarely observed during follow-up after bipolar RF treatment. The adverse reactions of multipolar RF therapy are similar to those of bipolar RF therapy. Both multipolar and bipolar RF therapy remain excellent options associated with short downtime and mild pain compared with other nonablative devices. Because of the rapid onset and short fixed distance of the action, some manufacturers have introduced a combination of a bipolar RF device and other cosmetic technologies to enhance the penetration and strengthen the effect. Combination approaches have several advantages. For example, RF energy is set at the lowest level to minimize adverse effects while preserving the desired efficacy. Additionally, pain and burning sensation are less severe during vacuum-assisted bipolar RF treatment. Moreover, RF devices with distanced multiple electrodes can achieve specific skin depths.
Nelson et al14 reported a case series in which 14 patients were treated with a bipolar dermal heating device using an RF handpiece (InMode Ltd., Irvine, CA, USA) for facial skin tightening, and the patients reported no adverse effects. According to the in vivo thermal view during the initial application, the RF handpiece released energy and treatment with a uniform heat distribution at 43°C. All patients showed mild to significant improvement at their follow-up visits.
Another study showed that percutaneous RF technology could be used to simultaneously ablate the subcutaneous fat and tighten the upper skin.15 In 2020, a multicenter trial confirmed the ability and safety of a percutaneous bipolar RF device (Serene Medical, Inc., Pleasanton, CA, USA) to improve the appearance of glabellar lines. The reduction in glabellar lines lasted for at least 3 months and was sustained for about 1 year. The infrequent adverse events included tenderness, swelling, bruising, and temporary paresthesia. However, it was a nonrandomized clinical trial, and the follow-up data were collected by telephone.16
A modified intramuscular insertion of a bipolar micro-needling RF device (Candela Medical, Wayland, MA, USA) was used to yield rejuvenated, tight skin with high satisfaction scores in all patients. This device delivered energy to the mimetic muscles; the local tissue temperature reached 67°C, and the epidermal temperature was maintained at 10°C. However, clinicians should be careful about the angle of microneedles deployed.17
One study used a multipolar RF and pulsed electromagnetic field synthesizer (Venus Freeze; Venus Concept, Toronto, ON, Canada) to rejuvenate aged skin among ten Korean patients who underwent eight treatment sessions over 6 weeks. A high satisfaction score calculated using questionnaires was reported. This study confirmed the efficacy and safety of the unique patterns of electro-optical synergy devices in facial rejuvenation treatment for East Asian patients.18
In another study, 30 patients underwent four multipolar, multifrequency RF treatments (MIP-880, Mimari, Inc., Poland) at 2-week intervals to improve their facial skin texture and eliminate rhytides. The authors reported a statistically significant improvement between measurements taken before and 3 months after the treatment without evident adverse effects.19
Fractional RF therapy
Minimally invasive fractional RF therapy delivers energy directly to the dermis, leaving the epidermis slightly injured. A fractional RF device exerts its effect through a microneedle or electrode arrays. A fractional RF micro-needle (FRM) device delivers the RF field using the electrode array to identify the source of symptoms in specific areas.20 This kind of RF energy has a maximum penetration depth of 3.5 mm. Noninsulated and insulated microneedles may be used in fractional RF devices. The noninsulated microneedle serves as the electrode, while the noninsulated microneedle device penetrates the dermis. Maximum thermal coagulation injury areas can be delivered to the targeted levels of the dermis except for the active tip of the microneedle. Conversely, insulated microneedle devices generate the energy flow through the tip of the needle.21 Fractional RF therapy is considered a relatively new method that is mainly applied to facial and cervical rejuvenation. It can also enhance the percutaneous absorption of drugs and accelerate wound healing. However, fractional RF devices have an increased risk of treatment-related pain, temporary erythema, and mild PIH. Nevertheless, the incidence of the most common adverse effect of FRM devices is still significantly lower than that of fractional laser treatment. A previous report described a rare case of prolonged erythema and inflammation lasting 18 months after FRM treatment. The use of FRM treatment with high energy levels may explain the infrequency of adverse reactions.22 To avoid these effects, lower energy is applied in areas close to the bone, such as the cheekbone, chin, and forehead.
A recent study involving Thai patients was performed to evaluate the efficacy of fractional RF therapy (SVC, Viora, Inc., New York, NY, USA) in facial skin tightening.23 This study confirmed the reliability of RF treatment among Asian patients with darker skin color.
Japanese researchers shared their clinical experience with the use of the fractional bipolar RF device eMatrix (Syneron Candela, Wayland, MA, USA) for improving facial wrinkles and sagging. In this study, two programs were designed and the differences between the two programs indicated a 5% or 10% coverage rate of RF energy. Each subject was treated every 4–6 weeks with a peak energy of 25 J using a 200-μm-diameter pin. Following treatment, obvious improvements were noted in the lateral canthus and lower eyelids, and only mild erythema was observed.24
A multicenter pilot study used fractionated RF with insulated microneedles (INFINI; Lutronic, Inc., Billerica, MA, USA) for lower facial rejuvenation treatment in a three-pass procedure. The entire procedure lasted 30 minutes and comprised about 1000 pulses, and each subject received a high RF energy of 11 J. Patient downtime was reduced to 12–48 hours, and adverse effects such as erythema or edema dissipated within a few days.25
In Japan, a multisource phase-controlled RF device (EndyMed Medical Ltd., Caesarea, Israel) that emits at a 1-MHz frequency at 1–65 W for skin laxity was used in a spilt-face study. After three rounds of treatment at a 1-week interval, the 3D images revealed notable improvement on the treated side. Histological analysis revealed a significant increase in the amount of elastin stain. Slight improvements were also present on the untreated side of the face.26
Combinations of RF therapy and other physical technologies
To achieve synergistic efficacy, some researchers have combined RF therapy with other physical cosmetic technologies. Ultrasound generates areas of intense heat and destroys the subcutaneous tissue. The penetration depth of ultrasound is generally deeper than that of RF. In some cases, the acting temperature is very high, such that the treatment process increases the risk of facial nerve injury. The combination of focused RF therapy and ultrasound for facial rejuvenation results in high overall patient satisfaction scores. In one study, the RF treatment efficacy was assessed using clinical photographs by three blinded physicians, and improved skin laxity was reported at different body parts.27
Korean researchers have demonstrated a synergistic effect of monopolar RF therapy and intense focused ultrasound in a single rejuvenation treatment session. The study recruited 22 women with a Fitzpatrick skin type of 3–4. A monopolar RF device called the Thermage CPT System (Solta Medical, Inc., Raleigh, NC, USA) was used, followed by application of the intense focused ultrasound device to lift the skin off the full facial area for about 300 treatment lines per face. Following treatment and a 4-month follow-up period, the assessed biopsy specimens indicated increased and thickened interstitial fibers throughout the dermis. The clinical assessment further revealed that mild or improved skin laxity was observed in 95% of the patients.28
Multimodality treatment combined with bipolar RF energy with optical energy, including intense pulsed light therapy and infrared diode laser therapy, has remarkable efficacy for improving erythema, telangiectasis, and skin texture. Twenty-six patients aged 36–63 years underwent four treatment sessions with an electro-optical synergy device (Triniti; Syneron Medical Ltd., Yokneam, Israel) for full-face rejuvenation at 4-week intervals. Analysis of the results was divided into objective and subjective assessments. Following treatment and a 6-month follow-up period, both the erythema index and transepidermal water loss (TEWL) value had significantly decreased, while the melanin index, stratum corneum moisture scores, and dermis moisture scores had progressively increased. These improvements were maintained for at least 6 months, and the patient satisfaction rate reached 88%.29
A combination of the INFINI and fractional 1927-nm thulium laser therapy has been used to eliminate loose skin. After the third and fourth sessions, apparent smoothing of wrinkles was seen in four middle-aged patients. The patients received RF energy (7.5 W, 30-ms exposure) followed by fractional 1927-nm thulium laser energy (5 W, 10 mJ) with six to eight passes in total. At the end of six treatment sessions and a 4-month follow-up period, the efficacy and safety of this combination therapy were confirmed.30
Mechanisms of RF therapy in rejuvenation
To achieve an optimal rejuvenation therapeutic effect, it is essential to regulate collagen contraction and accurately shrink the volume and number of adipocytes. The primary mechanism of various RF methods is based on focused tissue heating to stimulate collagen denaturation, remodeling, contraction, and regeneration.31 An RF device transfers actively charged particles to target structures through electromagnetic waves and forces particles to collide for heat generation.6 The RF energy penetration depth, which depends on the bioimpedance of tissues, RF type, and initial RF energy settings, is related to the acting temperature. Bioimpedance increases in the order of water, nerves, muscles, collagen, and fat. The penetration depth is inversely proportional to the frequency when the impedance is fixed, meaning that RF therapy at lower frequencies leads to deeper penetration.5
To permanently and noninvasively ameliorate wrinkles and skin laxity, the most critical orientation is the deep dermis and subcutaneous soft tissue layer. When RF energy deposits, soft tissues may reach maximum contraction in the interstitial space between two layers.32 Earlier monopolar RF devices had poor controllability of energy in deep skin, releasing energy on superficial skin to indirectly heat the dermis and thus impairing the epidermis; the most appropriate temperature for collagen contraction, therefore, could not be achieved. Application of RF devices in a reverse trapezoid manner can help to heat deeper skin and avoid epidermal ablation and denaturation of collagen fibrils.13 Some adipocyte-selective devices are designed to concentrate on the fat tissue layer, which enables the fat tissue to heat up faster than other blood-rich tissue layers such as the skin and muscle. This selective electrothermolysis keeps the local temperature at a relatively low level and accurately heats the targeted layer without damaging the surrounding structures.
Fibroblasts can produce more collagen at internal temperatures above 42°C. RF thermal energy acting on the skin leads to a series of changes: When they are within the appropriate temperature range, collagen fibrils contract immediately, although this contraction is only temporary based on the breakage of the intramolecular hydrogen bonds and the change in the helical structure. Histological analysis reveals that RF thermal stimulation contributes to short-term local microinflammatory stimulation of fibroblasts, and new collagen and elastin are produced in the long term.33 The Exilis Elite (BTL Industries Inc., Boston, MA, USA), a monopolar RF device mentioned earlier in this review, was used on pigs’ abdominal areas once per week for 4 weeks, and the collagen volume of skin samples was calculated. The results indicated that the collagen volume increased from 9.0% before therapy to 25.9% at 3 months after therapy. In this study, multi-pass and low-energy monopolar RF treatment caused the most apparent collagen contraction.33
The use of RF therapy for aging skin is effective in inducing collagen regeneration. One of the underlying mechanisms is encouragement of the expression of transforming growth factor β,34 which can promote the growth of dermal collagen and stimulate tissue repair. Treatment with bipolar fraction RF led to up-regulation of the Sirtuin gene family, which is involved in the regulation of a variety of anti-aging processes and a decrease in the expression of the apoptosis-related FoxO3 and p53 genes.35 RF thermal stimulation also enhanced adipocyte metabolism and the degradation of adipose triglyceride lipase. Induction of fat cell apoptosis may be another mechanism.6
Applications of RF therapy in esthetics
The first use of RF therapy in the field of dermatology was for improvement of skin photoaging. RF therapy has since been used in facial rejuvenation, treatment of uneven skin tone, face and body contouring, and treatment of unsightly skin diseases. Additionally, RF therapy manipulates the skin cooling system and can thus serve as a beneficial esthetic tool for heating and reducing fat tissue.
Several new monopolar RF devices have been engineered for combination with microneedles to protect tissues from high levels of heat energy. A new RF device called AGNES (Gowoonsesang Cosmetics Co., Ltd., Seoul, South Korea) reportedly performs well in treating periorbital wrinkles. One study revealed progressive positive changes in periorbital wrinkles with use of the AGNES device, and also showed that a monopolar RF device with a long microneedle (1.5 mm) performed better than a short microneedle (0.8 mm) in terms of decreasing the wrinkle score.36 The portability and practicality of RF therapy in the upper face areas have also been revealed. A study by Gold et al confirmed significant effects after RF rejuvenation treatment in periorbital areas. Nobile et al11 also reported a good curative effect in skin tightening of the forehead after unipolar RF treatment.
Lower face and neck
A recent single-center retrospective comparative study demonstrated that treatment with a fractional RF device (Scarlet S; Viol Co., Ltd., Seongnam-si, South Korea) was more effective for lower face areas than was treatment with a fractional erbium yttrium aluminum garnet laser. The assessments showed no significant change in demographic data between the two treatment groups. However, the reduction of wrinkles in the perioral, nasolabial, and jawline areas was quite evident after fractional RF treatment. Most patients expressed high satisfaction with fractional RF therapy. Adverse effects, including erythema, edema, and dryness, were not apparent in the fractional RF group.21 The findings of this study were consistent with the results obtained from previous studies.
Jiang et al37 demonstrated improvements in moderate lower facial wrinkles and laxity as measured by TEWL after at least 5 months of fractional RF therapy (eMatrix; Syneron Candela) and two follow-up periods. No significant difference was found between TEWL at baseline and after treatment. Nevertheless, the patients reported improved skin texture and were satisfied with the treatment. However, the sample size was limited to only 22 patients.
In a single-blind randomized controlled clinical trial, researchers implied that lower facial wrinkles in adult women showed no significant changes after fractional bipolar RF therapy. One of the designed test groups was based on the association between RF therapy with low-level laser therapy; however, low-level laser therapy did not enhance the effect of RF treatment.38 The negative results of this trial were related to the very short duration of treatment, and the long-term effect was not investigated.
The efficacy and safety of high-intensity focused RF devices for lower facial and neck skin laxity were strongly affirmed in another study.39 Although it was not a split-face or comparative study, the results nonetheless deserve consideration.
Limbs and trunk
A previous review highlighted the fact that RF devices can be used to effectively reduce fat tissues, especially in the abdomen and thighs.40 A non-contact RF device referred to as enCurve1 (Lutronic, Inc.) was used to deliver an RF field to selectively reduce abdominal fat and relatively improve body contouring without affecting the epidermis and dermis.41 An RF device at 27.12-MHz frequency was reported to selectively and effectively reduce abdominal fat in the epidermis, dermis, and adnexal structures of pigs. The results showed a 70% decrease in the adipose tissue layer with no impact on the serum levels of glucose, urea, liver function, and other routine lipid markers after four 30-minute treatments.42 Some researchers have also shown that focused monopolar RF devices play an important role in labial tissue tightening.43
Acne scars and other conditions
Other skin diseases can affect facial esthetics. Acne vulgaris is commonly seen in adolescents and has heavy psychosocial burdens. Notably, acne vulgaris often continues to adulthood and causes permanent scar formation. One type of acne scar is the atrophic scar, which can be subdivided into icepick, rolling, and boxing scars. Collagen remodeling induced by RF thermal stimulation can soften rolling acne scars and icepick scars with minor adverse effects.44 RF devices also facilitate drug delivery in dyschromia, such as melasma and PIH. The risk of hyperpigmentation is negligible after three fractional RF treatments at a 3-week interval.45
Strengths and limitations
RF therapy has been successfully applied to improve skin esthetics. Compared with conventional rejuvenation methods, such as ablative laser therapy and surgery, RF treatment has many benefits for skin rejuvenation, body contouring, and weight reduction. RF therapy is a safe and effective approach that improves facial rejuvenation in patients of different ages worldwide. Because of its “colorblind” property, RF treatment can be applied to people with multiple skin colors or skin types. RF therapy is not affected by the skin pigment content and hence does not affect pigment formation after treatment. Importantly, RF therapy is a noninvasive or minimally invasive tool that does not induce scar formation after treatment. Some novel RF devices can directly heat the targeted tissue layer without affecting the overlying skin, greatly minimizing the incidence of adverse effects and complications. Therefore, this technique significantly minimizes patient downtime to only hours or several days. In previous studies, the total treatment duration ranged from 1 week to 6 months. The effects of RF treatment can last for a long time. The emergence of home-use RF devices has made RF treatment more convenient and practical. With the exception of existing skin problems, RF therapy can bolster the skin against future aging.
However, several limitations should be discussed. Although positive outcomes of RF treatment have been reported by many researchers, some studies did not provide clear statistical evidence. Moreover, only a few studies were randomized controlled trials. Some studies drew conclusions based on physicians’ assessments and patient satisfaction, which might not be adequately objective. Moreover, several brands and models of RF devices with different setting parameters exist on the market, making their treatments nonuniform. For example, the temperature, duration of heating action, and number of repeat operations in the same regions are based on suggestions provided by manufacturers. Some adverse effects of RF treatment have been reported, such as mild to moderate pain during treatment, temporary edema, erythema, and occurrence of PIH after treatment. Such unwanted adverse effects can be minimized by applying personalized RF energy to different facial areas and using RF devices with a cooling system. Postoperative care should be enhanced to reduce the rate of adverse reactions. There are few persistent and severe adverse effects of RF therapy. Extending the follow-up time in further studies may allow for further elucidation of the long-term efficacy and safety of RF. Another limitation is that topical anesthetics are needed when using some types of RF devices, such as micro-needling fractional RF devices. Therefore, standardized preoperative and postoperative analgesia regimens should be developed.
To improve skin rejuvenation, it is essential to develop individualized and rational treatment strategies among numerous cosmetic treatment options. The most prominent feature of RF therapy is selective electrothermolysis. Therefore, RF devices can accurately heat specific layers of tissues, resulting in collagen contraction and skin tightening. There are several advantages of RF devices in treating facial skin laxity, wrinkles, and striae. RF treatment has long-lasting effects, few adverse effects, and short patient downtime, especially when compared with traditional invasive treatments. However, therapeutic standards and operation specifications of RF therapy have not been unified. Therefore, more extensive controlled experimental evidence needs to be established to further explore the utility of RF therapy. RF therapy is a safe and efficient facial rejuvenation method that deserves to be studied for broader application.
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. Lolis MS, Goldberg DJ. Radiofrequency in cosmetic dermatology: a review. Dermatol Surg 2012;38 (11):1765–1776. doi:10.1111/j.1524-4725.2012.02547.x.
. Sachs DL, Varani J, Chubb H, et al. Atrophic and hypertrophic photoaging: clinical, histologic, and molecular features of 2 distinct phenotypes of photoaged skin. J Am Acad Dermatol 2019;81 (2):480–488. doi:10.1016/j.jaad.2019.03.081.
. Shin JW, Kwon SH, Choi JY, et al. Molecular mechanisms of dermal aging and antiaging approaches. Int J Mol Sci 2019;20 (9):2126. doi:10.3390/ijms20092126.
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. McDaniel D, Weiss R, Weiss M, et al. Two-treatment protocol for skin laxity using 90-Watt dynamic monopolar radiofrequency device with real-time impedance intelligence monitoring. J Drugs Dermatol 2014;13 (9):1112–1117.
. Gold MH, Biron J, Levi L, et al. Safety, efficacy, and usage compliance of home-use device utilizing RF and light energies for treating periorbital wrinkles. J Cosmet Dermatol 2017;16 (1):95–102. doi:10.1111/jocd.12299.
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