title: Histologic analysis of the thermal effect on epidermal and dermal structures following treatment with the superpulsed CO2 laser and the erbium: YAG laser: an in vivo study.
abstract: OBJECTIVE
  To compare the in vivo histologic effects of the carbon dioxide (CO2) and erbium:yttrium aluminum garnet (Er:YAG) lasers. To ascertain the effects of combining CO2 and Er:YAG laser modalities during a single treatment session.
  
  
  METHODS
  Ten patients underwent laser treatment to four left preauricular sites 7 days prior to rhytidectomy as follows: CO2 alone, CO2/Er:YAG, Er:YAG alone, and Er:YAG/CO2. The right preauricular area was identically treated 1 hour prior to rhytidectomy. Laser treated skin was excised during rhytidectomy and was evaluated histopathologically in a blinded manner.
  
  
  RESULTS
  After 7 days, all groups were reepithelialized and showed equal neo-collagen formation. After 7 days, CO2/Er:YAG and Er:YAG alone had the least collagen injury and thickest epidermis and papillary dermis of all groups. Specimens lased 1 hour prior to excision showed the least collagen injury and thermal necrosis when treated with CO2/Er:YAG and Er:YAG alone. Four passes with CO2 removed 250 microm of tissue, while eight passes with the Er:YAG removed 160 microm of tissue.
  
  
  CONCLUSIONS
  Limiting CO2 laser passes and ending with Er:YAG produces less collagen injury, less thermal necrosis, and more robust epithelial and dermal fibrous tissue regeneration. CO2 followed by Er:YAG has similar thermal necrosis and collagen injury as Er:YAG alone, presumably due to Er:YAG removal of CO2 induced thermal injury.
authors: Division of Otolaryngology/Head and Neck Surgery, Facial Plastic and Reconstructive Surgery, Stanford University Medical Center, Palo Alto, California 94305, USA. heartburn@california.com
authors: D S
authors: DS
authors: Utley
authors: R J
authors: RJ
authors: Koch
authors: B M
authors: BM
authors: Egbert
mesh_terms: D020405:Dermis / Q000473:pathology* / Q000601:surgery; D004817:Epidermis / Q000473:pathology* / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053685:Laser Therapy; D008297:Male; D008875:Middle Aged; D015361:Rhytidoplasty / Q000379:methods*