title: Effect of Er:YAG laser on enamel acid resistance: morphological and atomic spectrometry analysis.
abstract: OBJECTIVE
  This study evaluated the effect of Er:YAG laser on enamel acid resistance.
  
  
  METHODS
  Seventy human enamel slabs were randomly divided into seven groups (n = 10): G1, Er:YAG laser (Key Laser 2, KaVo, Germany) 60 mJ, 2 Hz, 33.3 J/cm2 (handpiece no. 2051, non-contact); G2, Er:YAG laser 80 mJ, 2 Hz, 44.4 J/cm2 (handpiece no. 2051, non-contact); G3, Er:YAG laser 120 mJ, 2 Hz, 66.6 J/cm2 (handpiece no. 2051, non-contact); G4, Er:YAG laser 64 mJ, 2 Hz, 20 J/cm2 (handpiece no. 2055, contact); G5, Er:YAG laser 86.4 mJ, 2 Hz, 26.9 J/cm2 (handpiece no. 2055, contact); G6, Er:YAG laser 135 mJ, 2 Hz, 42.2 J/cm2 (handpiece no. 2055, contact); G7, control. After laser irradiation, samples were submitted to an acid challenge. For both the nos. 2051 and 2055 handpieces, irradiation was performed with a water cooled spray (5.0 ml/minutes). The calcium and phosphorous ions delivered from the tooth surface were quantified by atomic emission spectrometry, and morphological analysis of the enamel surface was performed under scanning electron microscopy. Kruskal-Wallis and multiple comparisons tests were applied to distinguish significant differences among the treatments (alpha = 5%).
  
  
  RESULTS
  Groups G1, G2, and G4 presented decreased demineralization. The SEM evaluation revealed different surface alterations as a result of the different energies used.
  
  
  CONCLUSIONS
  Lower energies can decrease enamel solubility without severe alterations of the enamel.
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, University of São Paulo (USP), São Paulo, SP, 05508-900, Brazil.
authors.forename: Renata Cristina M
authors.initials: RC
authors.lastname: Cecchini
authors.forename: Denise Maria
authors.initials: DM
authors.lastname: Zezell
authors.forename: Elisabeth
authors.initials: E
authors.lastname: de Oliveira
authors.forename: Patricia M
authors.initials: PM
authors.lastname: de Freitas
authors.forename: Carlos de P
authors.initials: Cde P
authors.lastname: Eduardo
mesh_terms: D000143:Acids; D003731:Dental Caries / Q000532:radiotherapy*; D003737:Dental Cavity Preparation / Q000379:methods; D003743:Dental Enamel / Q000528:radiation effects*; D004871:Erbium; D006801:Humans; D028022:Low-Level Light Therapy / Q000379:methods*; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D008963:Molar / Q000648:ultrastructure*; D012494:Sampling Studies; D013718:Tensile Strength
chemical_list: D000143:Acids; D004871:Erbium