title: [In vitro effect of pulse Nd: YAG laser plus NaF on ultrastructure and fluoride distribution of enamel].
abstract: OBJECTIVE
  To investigate the effect of pulse Nd: YAG laser combined with NaF on caries resistance of human enamel in vitro.
  
  
  METHODS
  24 caries-free, constant premolares were cut into enamel mass. Surface ultrastructure and fluoride distribution of enamel in laser-NaF treated group, laser treated group, NaF treated group and control group were observed by scanning electron microscope (SEM) and electron probe microanalyzer.
  
  
  RESULTS
  (1) SEM observation: In laser-NaF treated group, the smear layer was almost removed, the enamel surface showed partially melted-like and bubble-like appearance, diffuse white-small particles distributed on enamel surface, and melted position, microcrack and microhole appeared whitely blocking-reflection. (2) Electron probe microanalyzer analysis: In enamel samples, the highest average Ci of F- and the hightest depth which F- entered in enamel were recorded in the laser-NaF treated group. The average Ci of F- in laser-NaF treated group was significantly increased compared with that in NaF-treated group or laser-treated group or control group (P < 0.001).
  
  
  CONCLUSIONS
  The pulsed Nd:YAG laser combined with sodium fluoride could make the enamel surface partially melt, change the structure of the crystal, enhance the absorption of fluoride, and clear smear layer. This technology may resist the caries.
authors.affiliation: Duping Hospital & Research Institute of Surgery, The Third Military Medical University, Chongqing 400042, China.
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.forename: Lu-chuan
authors.initials: LC
authors.lastname: Liu
mesh_terms: D003743:Dental Enamel / Q000648:ultrastructure*; D005459:Fluorides / Q000737:chemistry*; D006801:Humans; D053844:Lasers, Solid-State; D016369:Smear Layer; D012969:Sodium Fluoride / Q000737:chemistry*
chemical_list: D012969:Sodium Fluoride; D005459:Fluorides