title: Effects of nanosecond pulsed Nd: YAG laser irradiation on dentin resistance to artificial caries-like lesions.
abstract: OBJECTIVE
  Previous investigations have demonstrated improved enamel caries resistance after laser irradiation. In this study, effects of nanosecond pulsed Nd:YAG laser irradiation on crown/root dentin susceptibility to caries-like lesions were investigated.
  
  
  METHODS
  Extracted human molar teeth were irradiated using a Q-switched nanosecond pulsed Nd:YAG laser. All teeth except controls were irradiated at: fluence, 1 or 5 J/cm2; spot size, 3 mm; and then subjected to demineralization. Measurements of caries lesion depth using scattering light microscopy and SEM were performed.
  
  
  RESULTS
  Lesion depth measurements did not differ significantly between controls and irradiated samples (P < 0.01), but SEM results showed some irradiation-induced alterations on crown and root dentin surfaces. Irradiated surfaces were partially melted, with sometimes narrowed or occluded tubules.
  
  
  CONCLUSIONS
  No consistent caries-protective effect of Q-switched nanosecond pulsed Nd:YAG laser irradiation on crown and root dentin was determined, but laser-induced morphological changes were observed.
authors.affiliation: Beckman Laser Institute and Medical Clinic, UC Irvine, California 92715, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Kimura
authors.forename: P
authors.initials: P
authors.lastname: Wilder-Smith
authors.forename: A M
authors.initials: AM
authors.lastname: Arrastia-Jitosho
authors.forename: L H
authors.initials: LH
authors.lastname: Liaw
authors.forename: K
authors.initials: K
authors.lastname: Matsumoto
authors.forename: M W
authors.initials: MW
authors.lastname: Berns
mesh_terms: D003731:Dental Caries / Q000517:prevention & control*; D003804:Dentin / Q000528:radiation effects* / Q000648:ultrastructure; D006801:Humans; D066298:In Vitro Techniques; D053685:Laser Therapy; D008855:Microscopy, Electron, Scanning