title: The efficacy of low-power lasers in tissue repair and pain control: a meta-analysis study.
abstract: OBJECTIVE
  We used statistical meta-analysis to determine the overall treatment effects of laser phototherapy on tissue repair and pain relief.
  
  
  BACKGROUND
  Low-power laser devices were first used as a form of therapy more than 30 years ago. However, their efficacy in reducing pain or promoting tissue repair remains questionable.
  
  
  METHODS
  Following a literature search, studies meeting our inclusion criteria were identified and coded. Then, the effect size of laser treatment, that is, Cohen's d, was calculated from each study using standard meta-analysis procedures.
  
  
  RESULTS
  Thirty-four peer-reviewed papers on tissue repair met our inclusion criteria and were used to calculate 46 treatment effect sizes. Nine peer-reviewed papers on pain control met the inclusion criteria and were used to calculate nine effect sizes. Meta-analysis revealed a positive effect of laser phototherapy on tissue repair (d = +1.81; n = 46) and pain control (d = +1.11; n = 9). The positive effect of treatment on specific indices of tissue repair was evident in the treatment effect sizes determined as follows: collagen formation (d = +2.78), rate of healing (d = +1.57), tensile strength (d = +2.13), time needed for wound closure (d = +0.76), tensile stress (d = +2.65), number and rate of degranulation of mast cells (d = +1.87), and flap survival (d = +1.95). Further, analysis revealed the positive effects of various wavelengths of laser light on tissue repair, with 632.8 nm having the highest treatment effect (d = +2.44) and 780 nm the least (d = 0.60). The overall treatment effect for pain control was positive as well (d = +1.11). The fail-safe number-that is, the number of studies in which laser phototherapy has negative or no effect-needed to nullify the overall outcome of this analysis was 370 for tissue repair and 41 for pain control.
  
  
  CONCLUSIONS
  These findings mandate the conclusion that laser phototherapy is a highly effective therapeutic armamentarium for tissue repair and pain relief.
authors.affiliation: School of Health Professions, Behavioral and Life Sciences, New York Institute of Technology, Old Westbury, NY 11568-8000, USA. Enwemeka@nyit.edu
authors.forename: Chukuka S
authors.initials: CS
authors.lastname: Enwemeka
authors.forename: Jason C
authors.initials: JC
authors.lastname: Parker
authors.forename: David S
authors.initials: DS
authors.lastname: Dowdy
authors.forename: Erin E
authors.initials: EE
authors.lastname: Harkness
authors.forename: Leif E
authors.initials: LE
authors.lastname: Sanford
authors.forename: Lynda D
authors.initials: LD
authors.lastname: Woodruff
mesh_terms: D005260:Female; D006801:Humans; D015601:Injury Severity Score; D028022:Low-Level Light Therapy / Q000379:methods*; D008297:Male; D010147:Pain Measurement; D010148:Intractable Pain / Q000175:diagnosis / Q000532:radiotherapy*; D016032:Randomized Controlled Trials as Topic; D018570:Risk Assessment; D012720:Severity of Illness Index; D016896:Treatment Outcome; D014945:Wound Healing / Q000528:radiation effects*; D014947:Wounds and Injuries / Q000175:diagnosis / Q000532:radiotherapy*