title: Split-face histological and biochemical evaluation of tightening efficacy using temperature- and impedance-controlled continuous non-invasive radiofrequency energy.
abstract: BACKGROUND
  Bipolar radiofrequency (RF) is capable of heating dermal collagen fibers and inducing skin tightening by collagen remodeling.
  
  
  OBJECTIVE
  To substantiate safety and improvement of skin laxity following skin heating with a novel temperature- and impedance-controlled non-invasive radiofrequency (RF) device by histological and biochemical evaluations.
  
  
  METHODS
  A split-face study was performed on 4 subjects who underwent 8 weekly RF sessions on one side of their face, leaving the other side an untreated control and then underwent facelift procedure. Clinical evaluation by photographs was done prior to the surgical procedure. Ex vivo fragments were harvested from both sides and compared. Morphometric analysis of dermal collagen fibers, collagen synthesis, and elastin synthesis evaluations were compared in triplicates.
  
  
  RESULTS
  Facial skin tightening was apparent in split-face photographs. A significant increase of 7.9% in dermal collagen content, and a significant increase of 34.7% in collagen synthesis were demonstrated in the treated samples. No statistically significant effect on elastin synthesis was detected.
  
  
  CONCLUSIONS
  Skin tightening following treatment with non-invasive RF has proven histologically and biochemically to derive from increase in dermal collagen synthesis and content.
authors.affiliation: a Department of Dermatology and Anatomical Pathology , Pitie Salpetiere Hospital and Institution GREDECO , Paris , France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Boisnic
authors.affiliation: b Department of Plastic and Maxillo-Facial Surgery , University Pitie Salpetiere , Paris , France.
authors.forename: Marc
authors.initials: M
authors.lastname: Divaris
authors.affiliation: c Institution GREDECO , Paris , France.
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Branchet
authors.affiliation: d Department of Dermatology , Tufts University School of Medicine, Private Practice Nelson Dermatology , St. Petersburg , FL , USA.
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Nelson
mesh_terms: D003094:Collagen / Q000378:metabolism* / Q000648:ultrastructure; D004549:Elastin / Q000096:biosynthesis; D017097:Electric Impedance; D005260:Female; D006801:Humans; D008875:Middle Aged; D010781:Photography; D000078702:Radiofrequency Therapy; D015361:Rhytidoplasty / Q000295:instrumentation / Q000379:methods*; D013696:Temperature
chemical_list: D003094:Collagen; D004549:Elastin
keywords: Radiofrequency; collagen remodeling; skin tightening