title: Effect of Nd:YAG radiation at millisecond pulse duration on dentine crater depth.
abstract: OBJECTIVE
  The effect of laser parameters on laser-dentine interaction has not been explored fully. This in vitro study investigated the effect on dentine crater depth of Nd:YAG laser radiation with varying repetition rates, total delivered energy, and dentine site either dyed or undyed.
  
  
  METHODS
  One hundred forty-four caries-free third molars were sectioned transversely to provide 288 upper and lower cut surfaces. The upper surfaces were dyed (IR5). These upper and lower cut surfaces were exposed to an Nd:YAG laser with a 7 millisecond (msec) pulse duration, pulse repetition rates (RR) of 2. 5, 5.4, and 10.5 Hz, and four total energies (2.28, 2.64, 3.6, 4.2 joules). Dentine crater depth was measured by using a Reflex microscope. Results were statistically analysed with analysis of variance.
  
  
  RESULTS
  Crater depth increased with increase in total delivered energy and in dyed and inner dentine sites (P<0.0001) but decreased with increasing repetition rate (P< 0.0001).
  
  
  CONCLUSIONS
  Increasing energy, dyed, and inner dentine sites produced deeper craters.
authors.affiliation: Department of Restorative Dentistry, Eastman Dental Institute and Hospital for Oral Health Care Sciences, University of London, London, United Kingdom. A.McDonald@eastman.ucl.ac.uk
authors.forename: A V
authors.initials: AV
authors.lastname: McDonald
authors.forename: N M
authors.initials: NM
authors.lastname: Claffey
authors.forename: G J
authors.initials: GJ
authors.lastname: Pearson
authors.forename: W
authors.initials: W
authors.lastname: Blau
authors.forename: D J
authors.initials: DJ
authors.lastname: Setchell
mesh_terms: D000704:Analysis of Variance; D003737:Dental Cavity Preparation / Q000379:methods*; D003762:Dental Instruments; D003804:Dentin / Q000528:radiation effects* / Q000601:surgery; D004871:Erbium; D006244:Hardness; D006801:Humans; D066298:In Vitro Techniques; D053685:Laser Therapy; D008963:Molar; D055585:Physical Phenomena; D010825:Physics
chemical_list: D004871:Erbium