title: Investigation of mast cells in human gingiva following low-intensity laser irradiation.
abstract: OBJECTIVE
  The aims of the present study were to investigate the effect of low-intensity laser irradiation on the total number of mast cells as well as the percentage of degranulation in human gingiva. Blood vessel dilation was also evaluated.
  
  
  BACKGROUND
  It has been proposed that low-intensity laser irradiation can ameliorate pain, swelling, and inflammation. In periodontal tissue, mast cells may influence either the destructive events or the defense mechanism against periodontal disease via secretion of cytokines and through cellular migration to improve the healing process. Mast cells play an important role in the inflammatory process.
  
  
  METHODS
  Twenty patients with gingival enlargement indicated for gingivectomy were selected. Gingival fragments were obtained from each patient and divided into three different groups before surgery. One fragment was removed without any irradiation. The two others were submitted to punctual irradiation with an energy density of 8 J/cm(2) at an output power of 50 mW at 36 Hz for 36 sec before gingivectomy. Nondegranulated and degranulated mast cells were counted in five areas of the gingival fragment connective tissue. Major and minor diameters of the blood vessels were also measured.
  
  
  RESULTS
  Both red and infrared radiation promoted a significant increase in mast cell degranulation compared to controls; however, no statistically significant differences (p > 0.05) were observed between the irradiated groups. No significant differences among the groups were observed regarding blood vessel size.
  
  
  CONCLUSIONS
  The results suggests that red and infrared wavelengths promote mast cell degranulation in human gingival tissue, although no dilation of blood vessels was observed. The effects of premature degranulation of mast cells in human tissue and the laser radiation protocol applied in this study encourage further investigations to extend these results into clinical practice.
authors.affiliation: IPEN-CNEN/SP, Cidade Universitária, São Paulo, Brazil.
authors.forename: L B
authors.initials: LB
authors.lastname: Silveira
authors.forename: R A
authors.initials: RA
authors.lastname: Prates
authors.forename: M D
authors.initials: MD
authors.lastname: Novelli
authors.forename: H A
authors.initials: HA
authors.lastname: Marigo
authors.forename: A A
authors.initials: AA
authors.lastname: Garrocho
authors.forename: J C F
authors.initials: JC
authors.lastname: Amorim
authors.forename: G R
authors.initials: GR
authors.lastname: Sousa
authors.forename: M
authors.initials: M
authors.lastname: Pinotti
authors.forename: M S
authors.initials: MS
authors.lastname: Ribeiro
mesh_terms: D000328:Adult; D015550:Cell Degranulation / Q000187:drug effects*; D005260:Female; D005881:Gingiva / Q000473:pathology / Q000528:radiation effects* / Q000601:surgery; D019214:Gingival Overgrowth / Q000532:radiotherapy* / Q000601:surgery; D005890:Gingivectomy; D006801:Humans; D028022:Low-Level Light Therapy; D008297:Male; D008407:Mast Cells / Q000528:radiation effects*; D008875:Middle Aged; D014664:Vasodilation / Q000187:drug effects