title: Subsurface morphologic changes of ND:YAG laser-etched enamel.
abstract: OBJECTIVE
  Etching the enamel surface with a Nd:YAG dental laser produces impact craters with cavities, micropores, and microfissures. This in vitro SEM study examined laser-etched enamel to determine the pattern and extent of subsurface changes.
  
  
  METHODS
  The facial surface of 10 maxillary central incisor teeth were coated with a black initiator and laser-etched with a pulsed Nd:YAG laser (1.06 lambda, 75 mJ, 15 Hz, 320 microns fiber, 94 J/cm2 fluence). The facial surface of five teeth were plastic-embedded under a low vacuum, then demineralized in 10% formic acid. The other teeth were split incisoapically. All samples were prepared for SEM.
  
  
  RESULTS
  Examination of the plastic impressions showed a delicate interlacing pattern of thin partitions and small knob-like expansions. Examination of the split teeth showed the penetration of microfissures into the enamel estimated at 10 microns.
  
  
  CONCLUSIONS
  These subsurface alterations may provide space for the infiltration and mechanical retention of dental resin.
authors.affiliation: Department of Biomedical Sciences, University of Detroit Mercy School of Dentistry, Michigan 48207, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Hess
mesh_terms: D003743:Dental Enamel / Q000528:radiation effects* / Q000648:ultrastructure; D006801:Humans; D066298:In Vitro Techniques; D007834:Lasers; D008855:Microscopy, Electron, Scanning