title: Study on acid resistance of human dental enamel and dentin irradiated by semiconductor laser with Ag(NH3)2F solution.
abstract: OBJECTIVE
  The purpose of this study was to investigate the acquired acid resistance of human dental enamel and dentin treated by 38% diamine silver fluoride [Ag(NH3)2F] solution and semiconductor (diode) laser irradiation in vitro.
  
  
  BACKGROUND
  There have been no reports on the acid-resistant effect by combined use of fluoride and semiconductor laser.
  
  
  METHODS
  Sixty crowns of extracted human molars were divided into two groups for enamel and dentin samples, and each group was subdivided into three subgroups of 10 each. Each subgroup of enamel and dentin samples served as a control; one was treated with Ag(NH3)2F and the other was treated with Ag(NH3)2F and semiconductor laser irradiation at 2 W for 30 sec. Then all samples were immersed in 5 ml of 0.1 M lactic acid (pH 4.8) at 37 degrees C for 24 h. The concentration of calcium ion (Ca2+) dissolved in the solution was measured by atomic absorption spectrophotometry, and the samples were observed by stereoscopy and scanning electron microscopy (SEM).
  
  
  RESULTS
  In both enamel and dentin samples, dissolved Ca2+ concentration in Ag(NH3)2F- or Ag(NH3)2F- and laser-treated group was significantly decreased compared with that in the control (p < 0.01). SEM findings showed that numerous cubic particles ranging from 0.1 to 0.5 mcirom were observed only in the combined treated groups of both enamel and dentin samples.
  
  
  CONCLUSIONS
  A significantly decreased solubility of human enamel and dentin was acquired after treatment by Ag(NH3)2F and semiconductor laser irradiation, which suggested that this combined use has the capability of a more efficient acid-resistant effect on human dental hard tissues.
authors.affiliation: Department of Endodontics, Showa University School of Dentistry Tokyo, Japan.
authors.forename: D G
authors.initials: DG
authors.lastname: Yu
authors.forename: Y
authors.initials: Y
authors.lastname: Kimura
authors.forename: A
authors.initials: A
authors.lastname: Fujita
authors.forename: M
authors.initials: M
authors.lastname: Hossain
authors.forename: J I
authors.initials: JI
authors.lastname: Kinoshita
authors.forename: N
authors.initials: N
authors.lastname: Suzuki
authors.forename: K
authors.initials: K
authors.lastname: Matsumoto
mesh_terms: D002327:Cariostatic Agents / Q000627:therapeutic use*; D003743:Dental Enamel / Q000528:radiation effects* / Q000648:ultrastructure; D003804:Dentin / Q000528:radiation effects*; D005459:Fluorides / Q000627:therapeutic use*; D006801:Humans; D019344:Lactic Acid; D053685:Laser Therapy; D018030:Silver Compounds / Q000627:therapeutic use*; D013054:Spectrophotometry, Atomic
chemical_list: D002327:Cariostatic Agents; D018030:Silver Compounds; C105022:silver fluoride; D019344:Lactic Acid; D005459:Fluorides