title: Enamel diffusion modulated by Er:YAG laser (Part 1)--FRAP.
abstract: Several studies have demonstrated the caries protective effect of lasers by strengthening enamel crystalline structure. However, the effect of laser on enamel diffusion (ED) remains unclear.
  
  
  OBJECTIVE
  This study aimed to quantify the laser-induced alteration of diffusion coefficients (DC) in enamel using fluorescence recovery after photobleaching (FRAP).
  
  
  METHODS
  Eleven caries-free enamel sections were characterized morphologically using stereomicroscopy, polarized light microscopy and scanning electron microscopy, before and after laser treatment with Er:YAG laser 50 mJ x 5 s x 5 Hz. With 20 microM fluorescein, DCs were measured (n=11) by FRAP coupled with confocal microscopy.
  
  
  RESULTS
  The DCs measured were 2.89+/-0.61 x 10(-7)cm(2)/s and 4.076+/-0.73 x 10(-7)cm(2)/s, at the lased and unlased areas, respectively (p=0.001).
  
  
  CONCLUSIONS
  This study has confirmed the reduction of ED as a potential mechanism involved in laser-induced caries prevention. FRAP was demonstrated to be a promising technique for evaluating diffusion-related phenomenon in enamel.
authors.affiliation: Department of Preventive Dentistry, Faculty of Dentistry, 5 Lower Kent Ridge Road, National University of Singapore, Singapore 119074, Singapore.
authors.forename: N L
authors.initials: NL
authors.lastname: Maung
authors.forename: T
authors.initials: T
authors.lastname: Wohland
authors.forename: C-Y S
authors.initials: CY
authors.lastname: Hsu
mesh_terms: D000465:Algorithms; D000704:Analysis of Variance; D003743:Dental Enamel / Q000737:chemistry / Q000528:radiation effects* / Q000648:ultrastructure; D005453:Fluorescence; D006801:Humans; D053685:Laser Therapy / Q000379:methods*; D053844:Lasers, Solid-State / Q000627:therapeutic use*