title: Minimally invasive skin rejuvenation with Erbium: YAG laser used in thermal mode.
abstract: OBJECTIVE
  To evaluate the efficacy and safety of a thermal mode Erbium:YAG laser several in-vivo morphological as well as clinical changes were monitored in a multi-center investigation.
  
  
  METHODS
  An Erbium:YAG laser was used at a thermal mode with sub-ablative fluences of 2.1 and 3.1 J/cm(2) with parallel air cooling to treat either periorbital, perioral rhytides or patients with post-traumatic or acne scars. Two treatments were applied 2 months apart, with follow-up at 1, 3, 6, and 12 months post-treatment. Photographs were taken before and at each follow-up visit and evaluated by three blinded independent reviewers. Histology and immunohistochemistry for pro-collagen expression were investigated. Optical coherence tomography (OCT) was performed before, and at 4, 14, and 28 days after single pass treatment with Erbium:YAG thermal pulses.
  
  
  RESULTS
  The improvement of rhytides at 1-3 months follow-up was graded as excellent in 19%, good in 19%, fair in 31%, and no improvement in 31%. At the 6- to 12-month follow-up, the improvement was excellent in 40%, good in 40%, fair in 20%, and no improvement in 0%. The improvement of scars at 3-6 months follow-up was graded as excellent in 50%, good in 25%, fair in 25%, and no improvement in 0%. Intra- and post-operative discomfort was described as mild by the patients. OCT, histological sections and immunohistochemistry demonstrated production of new collagen bundles.
  
  
  CONCLUSIONS
  Thermal Erbium:YAG pulses can induce collagen neogenesis, as proved by temperature elevation and morphological changes in the upper dermis. This leads clinically to visible and long lasting reduction of wrinkles and scars after applying multiple passes with minimal side-effects.
authors.affiliation: Institute for Laser Technologies in Medicine and Metrology, University of Ulm, Germany. karin.rapp@ilm.uni-ulm.de
authors.forename: Karin
authors.initials: K
authors.lastname: Kunzi-Rapp
authors.forename: Christine C
authors.initials: CC
authors.lastname: Dierickx
authors.forename: Bernard
authors.initials: B
authors.lastname: Cambier
authors.forename: Michael
authors.initials: M
authors.lastname: Drosner
mesh_terms: D000328:Adult; D000368:Aged; D002921:Cicatrix / Q000532:radiotherapy*; D003198:Computer Simulation; D004307:Dose-Response Relationship, Radiation; D004871:Erbium; D005260:Female; D006801:Humans; D053685:Laser Therapy / Q000295:instrumentation / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009010:Monte Carlo Method; D011347:Procollagen / Q000378:metabolism; D011879:Radiotherapy Dosage; D012867:Skin / Q000166:cytology / Q000528:radiation effects; D015595:Skin Aging / Q000528:radiation effects*; D041623:Tomography, Optical Coherence; D016896:Treatment Outcome
chemical_list: D011347:Procollagen; D004871:Erbium