title: Does a pulsed mode offer advantages over a continuous wave mode for excisional biopsies performed using a carbon dioxide laser?
abstract: OBJECTIVE
  Animal studies of excisional biopsies have shown less thermal damage when a carbon dioxide (CO(2)) laser (10.6 μm) is used in a char-free (CF) mode than in a continuous-wave (CW) mode. The authors' aim was to evaluate and compare clinical and histopathologic findings of excisional biopsies performed with CW and CF CO(2) laser (10.6 μm) modes.
  
  
  METHODS
  This prospective randomized controlled clinical trial included 60 patients with similar fibrous hyperplasias of the buccal plane willing to undergo excisional CO(2) laser biopsy. Patients were randomly allocated to the CW (5 W) or CF (140 Hz, 400 μs, 33 mJ) group. Duration of surgery, intra- and postoperative complications, and the width (micrometers) of the histopathologic collateral thermal damage zone were registered as primary outcome variables. Secondary outcome variables were pain (patients filled in a visual analog scale [VAS]) and analgesic intake (recorded by patients).
  
  
  RESULTS
  The study group consisted of 36 women and 24 men with a median age of 50.5 years. Median durations of surgery were 74.5 seconds in the CW group and 83.5 seconds in the CF group. Intraoperative venous bleeding occurred in 16.7% of patients in the CW group and in 13.3% of patients in the CF group. Median areas of histopathologic collateral damage zones were similar in the CW group (166.5 μm) and the CF group (162.5 μm). There was no statistically significant difference between the VAS values of the 2 groups. Analgesic intake was recorded by 16.7% of patients in the CW group and by 6.7% of patients in the CF group (P = .23, not significant). No statistically significant correlation was found between areas of thermal damage zones and postoperative VAS scores.
  
  
  CONCLUSIONS
  In contrast to previous animal studies, no significant difference was found in the widths of thermal damage zones between the CW and CF groups. The VAS values and analgesic intake were low in the 2 groups. The 2 CO(2) laser modes are appropriate for the excision of intraoral mucosal lesions. A safety border of at least 1 mm is recommended regardless of the laser mode used.
authors.affiliation: Department of Oral Surgery and Stomatology, School of Dental Medicine, University of Bern, Bern, Switzerland.
authors.forename: Valerie G A
authors.initials: VG
authors.lastname: Suter
authors.forename: Hans Jörg
authors.initials: HJ
authors.lastname: Altermatt
authors.forename: Thomas
authors.initials: T
authors.lastname: Dietrich
authors.forename: Peter A
authors.initials: PA
authors.lastname: Reichart
authors.forename: Michael M
authors.initials: MM
authors.lastname: Bornstein
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000700:Analgesics / Q000627:therapeutic use; D001706:Biopsy / Q000379:methods*; D016063:Blood Loss, Surgical; D004487:Edema / Q000209:etiology; D005260:Female; D005355:Fibrosis; D005500:Follow-Up Studies; D006801:Humans; D006965:Hyperplasia; D053685:Laser Therapy / Q000379:methods*; D054020:Lasers, Gas / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009061:Mouth Mucosa / Q000473:pathology / Q000601:surgery*; D010147:Pain Measurement; D010149:Postoperative Pain / Q000209:etiology; D011183:Postoperative Complications; D011446:Prospective Studies; D013997:Time Factors; D016896:Treatment Outcome; D014945:Wound Healing / Q000502:physiology
chemical_list: D000700:Analgesics