title: Evaluation of the Morphological Characteristics of Laser-Irradiated Dentin.
abstract: OBJECTIVE
  The aim of this study was to investigate the effect of different energy settings of Er:YAG laser irradiation on dentin surface morphology with respect to the number of opened dentinal tubules.
  
  
  BACKGROUND
  An ideally prepared dentin surface with opened dentinal tubules is a prerequisite for adhesive fixation. No study, however, has yet compared the numbers of opened dentinal tubules with regard to statistical differences.
  
  
  METHODS
  Conventional preparations using a bur with or without additional acid etching acted as control groups. Dentin specimens were prepared from human third molars and randomly divided into eight groups according to the energy settings of the laser (1, 1.5, 4, 6, 7.5, and 8 W) and two controls (bur and bur plus acid etching). After surface preparation, dentin surfaces were analyzed with a scanning electron microscope, and the number of opened dentinal tubules in a defined area was counted.
  
  
  RESULTS
  The control groups showed smooth surfaces with (bur plus acid etching) and without opened dentinal tubules (bur), whereas all laser-irradiated surfaces showed rough surfaces. Using the energy setting of 4 W resulted in significantly more opened dentinal tubules than the conventional preparation technique using the bur with additional acid etching. In contrast, the energy setting of 8 W showed significantly fewer opened dentinal tubules, and also exhibited signs of thermal damage.
  
  
  CONCLUSIONS
  The Er:YAG laser with an energy setting of 4 W generates a dentin surface with opened dentinal tubules, a prerequisite for adhesive fixation.
authors.affiliation: 1 Department of Conservative Dentistry & Periodontology, Medical University of Vienna , Vienna, Austria .|2 Department of Preventive, Restorative and Pediatric Dentistry, School of Dentistry, University of Bern , Bern, Switzerland .
authors.forename: Barbara
authors.initials: B
authors.lastname: Cvikl
authors.affiliation: 1 Department of Conservative Dentistry & Periodontology, Medical University of Vienna , Vienna, Austria .
authors.forename: Bledar
authors.initials: B
authors.lastname: Lilaj
authors.affiliation: 1 Department of Conservative Dentistry & Periodontology, Medical University of Vienna , Vienna, Austria .
authors.forename: Alexander
authors.initials: A
authors.lastname: Franz
authors.affiliation: 1 Department of Conservative Dentistry & Periodontology, Medical University of Vienna , Vienna, Austria .
authors.forename: Daniela
authors.initials: D
authors.lastname: Degendorfer
authors.affiliation: 1 Department of Conservative Dentistry & Periodontology, Medical University of Vienna , Vienna, Austria .
authors.forename: Andreas
authors.initials: A
authors.lastname: Moritz
mesh_terms: D000293:Adolescent; D000328:Adult; D003804:Dentin / Q000737:chemistry* / Q000528:radiation effects*; D006801:Humans; D053844:Lasers, Solid-State; D008963:Molar / Q000737:chemistry / Q000528:radiation effects; D011897:Random Allocation; D055815:Young Adult