title: Micro-CT evaluation of cavities prepared with with different Er:YAG handpieces.
abstract: OBJECTIVE
  The aim of the study was to compare several cavity shapes after application using different handpieces and tips of Er:YAG laser.
  
  
  METHODS
  Firstly, this in vitro investigation was performed on two upper molars. Their crowns were cut horizontally underneath the occlusal fissures in order to obtain a flat dentin surface. Afterwards, minimal cavities were prepared by using an Er:YAG laser device with a variety of handpieces and tips (Kavo KEY Laser Plus). All cavities were prepared using the following parameters: 250 mJ and 10 Hz during 30s, and were scanned using Micro-CT. Secondly, thirteen caries-free, human upper molars were prepared according to the same protocol. Five cavities were prepared on each tooth, using five different tips and the same laser settings as step one. The cavities' depths were measured with a digital micrometer. The width and morphology were controlled under scanning electron microscope (SEM).
  
  
  RESULTS
  Noticeable differences in the dimensions of the cavities were observed, even if the same laser parameters were used for all preparations. Two main shapes were registered: triangle and rectangle.
  
  
  CONCLUSIONS
  None of the cavities presented an adhesive configuration, rounded shape often found in hidden caries; they were straighter (rectangle) or focusing (triangle). For the moment, there is no ideal Er:YAG laser handpiece/tip in order to prepare conservative adhesive cavity.
authors.affiliation: General Dentist, London, United Kingdom.
authors.forename: L
authors.initials: L
authors.lastname: Savatier
authors.affiliation: Division of Cariology and Endodontology, University of Geneva, Geneva, Switzerland.
authors.forename: F
authors.initials: F
authors.lastname: Curnier
authors.affiliation: Division of Cariology and Endodontology, University of Geneva, Geneva, Switzerland.
authors.forename: I
authors.initials: I
authors.lastname: Krejci
mesh_terms: D003731:Dental Caries / Q000000981:diagnostic imaging*; D006801:Humans; D053844:Lasers, Solid-State; D008855:Microscopy, Electron, Scanning; D055114:X-Ray Microtomography / Q000379:methods*