title: Viability of human septal cartilage after 1.45 microm diode laser irradiation.
abstract: OBJECTIVE
  Chondrocyte viability following laser irradiation and reshaping has not been established for human nasal septal cartilage. Knowledge of the relationship between thermal injury and laser dosimetry is needed in order to optimize septal laser cartilage reshaping. The objective of this study was to determine the depth and width of thermal injury in human septal cartilage following laser irradiation.
  
  
  METHODS
  Excess fresh nasal septal cartilage sections from rhinoplasty or septoplasty operations were irradiated using a 1.45 microm diode laser 1.25-3.6 W (2.8 mm spot diameter) with 1 second fixed exposure time, and then at exposure times of 1-4 seconds for a fixed power of 1.25 W. An infrared camera recorded surface temperature profiles during irradiation, and the temperature data were incorporated into a rate process model to numerically estimate thermal damage. Calcein AM and ethidium homodimer-1 fluorescent dyes combined with confocal laser microscopy (CLM) were used to measure thermal damage.
  
  
  RESULTS
  CLM demonstrated clear demarcation between dead and living cells following irradiation. The extent of non-viable chondrocyte distributions increased with power and exposure time. The maximum depths of injury were 1,012 and 1,372 microm after 3.6 W 1 second and 1.25 W 4 seconds irradiation respectively. The damage predictions made by the rate process model underestimated thermal injury when compared with CLM measurements.
  
  
  CONCLUSIONS
  The assay system identified regions of non-viable chondrocytes in human septal cartilage and defined how thermal injury varies with dosimetry when using a 1.45 microm diode laser.
authors.affiliation: Department of Otolaryngology, Head and Neck Surgery, Seoul Paik Hospital, Inje University, 5 Mareunnae Gil, Jung Gu, Seoul 100032, Korea. cisoo99@yahoo.co.kr
authors.forename: Ick-Soo
authors.initials: IS
authors.lastname: Choi
authors.forename: Yong-Seok
authors.initials: YS
authors.lastname: Chae
authors.forename: Allison
authors.initials: A
authors.lastname: Zemek
authors.forename: Dmitry E
authors.initials: DE
authors.lastname: Protsenko
authors.forename: Brian
authors.initials: B
authors.lastname: Wong
mesh_terms: D006801:Humans; D054023:Lasers, Semiconductor; D055171:Nasal Cartilages / Q000528:radiation effects*; D014022:Tissue Survival
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