title: The use of Er:YAG laser for cavity preparation: an SEM evaluation.
abstract: OBJECTIVE
  The purpose of this study was to evaluate morphological changes in cavities prepared by the Er:YAG laser (2.94 mum) at different parameters of irradiation and by a diamond bur.
  
  
  METHODS
  Cavities were prepared on 27 human molars (n = 3): G1, 15 Hz/160 mJ enamel/6 Hz/200 mJ dentin; G2, 15 Hz/180 mJ enamel/6 Hz/200 mJ dentin; G3, 15 Hz/160 mJ enamel/6 Hz/250 mJ dentin; G4, 15 Hz/180 mJ enamel/6 Hz/250 mJ dentin; G5, 15 Hz/180 mJ enamel/10 Hz/180 mJ dentin; G6, 15 Hz/160 mJ enamel/10 Hz/180 mJ dentin; G7, 15 Hz/160 mJ enamel/10 Hz/160 mJ dentin; G8, 15 Hz/180 mJ enamel/10 Hz/160 mJ dentin; G9, diamond bur. For SEM analysis, samples were fixed (2.5% glutaraldheyde, 12 h, 4 degrees C), dehydrated (25-100% ethanol), dried, and sputter-coated with gold.
  
  
  RESULTS
  Despite the changes on energy and repetition-rate settings, all laser-treated samples showed no evidence of thermal damage or signs of burning and melting. Er:YAG laser ablated dental hard tissues showed exposed enamel prisms, dentin surface without smear layer, and opened dentinal tubules.
  
  
  CONCLUSIONS
  Different Er:YAG laser parameters were effective for ablation of hard tissues, creating an irregular and microretentive morphological pattern without hard tissue damage.
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, University of São Paulo, São Paulo, Brazil.
authors.forename: Patricia Moreira
authors.initials: PM
authors.lastname: Freitas
authors.forename: Ricardo Scarparo
authors.initials: RS
authors.lastname: Navarro
authors.forename: Juliana Almeida
authors.initials: JA
authors.lastname: Barros
authors.forename: Carlos
authors.initials: C
authors.lastname: de Paula Eduardo
mesh_terms: D003737:Dental Cavity Preparation / Q000379:methods*; D003743:Dental Enamel / Q000648:ultrastructure*; D003804:Dentin / Q000648:ultrastructure*; D006801:Humans; D053844:Lasers, Solid-State; D008855:Microscopy, Electron, Scanning; D008963:Molar