title: Quantitative evaluation of intact peripheral nerve structures after utilization of CO2 laser, electrocautery, and scalpel.
abstract: OBJECTIVE
  This study aimed to evaluate quantitatively the integrity of nerve structures near CO2 laser incisions.
  
  
  BACKGROUND
  There are some hypotheses that try to explain the analgesia reported after CO2 laser surgery. One of them is based upon the observation of the destruction of nerve endings after use of this technique.
  
  
  METHODS
  A comparative study was carried out using 25 animals (Rattus norvegicus) divided into five groups of 5 animals each. Standard incisions were carried on the dorsum of the tongue of each animal using the cautery (group 2), scalpel (group 3), CW CO2 laser (group 4), and SPS CO2 (group 5); group I served as control. The animals were killed immediately after the experiment, and specimens were taken and routinely processed to wax. Three-micrometer sections were cut and stained using S-100 protein antibody. The stained sections were analyzed under light microscopy using a calibrated graticule, and the number of intact nerves was counted in five standard areas around the incision.
  
  
  RESULTS
  The results of this study showed that there were no statistically significant differences in the numbers of intact peripheral nerve structures in both laser groups and other groups. No statistically significant difference was found between nonoperated and scalpel groups. The number of intact peripheral structures in cautery wounds was significantly smaller than in non-operated and scalpel wounds.
  
  
  CONCLUSIONS
  Therefore, it is unlikely that immediate destruction of peripheral nerve structures is the cause of post-operative analgesia following CO2 laser surgery.
authors.affiliation: School of Dentistry, Center of Laser of the Federal University of Bahia, Salvador, BA, Brazil.
authors.forename: E A
authors.initials: EA
authors.lastname: Rocha
authors.forename: A L
authors.initials: AL
authors.lastname: Pinheiro
authors.forename: M G
authors.initials: MG
authors.lastname: Oliveira
mesh_terms: D000818:Animals; D002245:Carbon Dioxide; D004564:Electrocoagulation / Q000009:adverse effects*; D005260:Female; D053685:Laser Therapy / Q000009:adverse effects*; D008297:Male; D010149:Postoperative Pain / Q000503:physiopathology; D059348:Peripheral Nerve Injuries; D051381:Rats
chemical_list: D002245:Carbon Dioxide