title: Influence of laser irradiation on pits and fissures: an in situ study.
abstract: OBJECTIVE
  The aim of this in situ study was to analyze the influence of the Er:YAG, Nd:YAG, and CO(2) lasers on the enamel acid resistance of pits and fissures.
  
  
  BACKGROUND
  The laser tissue interaction has been studied as a method of preventing occlusal caries.
  
  
  METHODS
  Thirteen volunteers wore palatal acrylic appliances containing human occlusal enamel blocks that were divided into four groups (G1, control; G2, Er:YAG; G3, Nd:YAG; G4, CO(2)). Each palatal acrylic appliance was used in the four studied groups and was used for 14 consecutive days. A sucrose solution was applied to the specimens six times per day. The specimens were then sectioned in half, and a microhardness test was applied. The other halves were analyzed using polarized light microscopy to measure the caries-like lesion areas, and a morphological analysis was conducted using a scanning electron microscope (SEM).
  
  
  RESULTS
  For the statistical analysis of the data obtained from the microhardness test (Knoop hardness number. [KHN]) (α=5%), Fisher's exact test was performed, and the group means were as follows: G1, 247±71; G2, 258±70; G3, 272±73; and G4, 298±56. The results demonstrated that the control group was significantly different from G3 and G4, which presented higher microhardness values. The Wilcoxon signed-rank test was used to analyze the data obtained from the caries-lesion area measurements (mm(2)) (α=5%) (G1, 0.01±1.08; G2, 0.13±0.18; G3, 0.05±0.17; and G4, 0.09±0.22). The results no showed significant differences among the groups in this analysis.
  
  
  CONCLUSIONS
  Based on the results from the present study, it may be concluded that the CO(2) and Nd:YAG lasers increased the enamel acid resistance in pits and fissures.
authors: Departamento de Odontologia Restauradora, Faculdade de Odontologia de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto-SP, Brazil.
authors: Alessandra M
authors: AM
authors: Correa-Afonso
authors: Jesus D
authors: JD
authors: Pécora
authors: Regina G
authors: RG
authors: Palma-Dibb
mesh_terms: D000328:Adult; D003731:Dental Caries / Q000532:radiotherapy; D003743:Dental Enamel / Q000528:radiation effects*; D003745:Dental Enamel Permeability / Q000528:radiation effects; D003750:Dental Fissures / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D053844:Lasers, Solid-State; D008297:Male; D008855:Microscopy, Electron, Scanning; D055815:Young Adult