title: A comparison between the occluding effects of the Nd:YAG laser and the desensitising agent sensodyne on permeation through exposed dentinal tubules of endodontically treated teeth: an in vitro study.
abstract: OBJECTIVE
  Dentine hypersensitivity may occur due to loss of covering enamel and/or loss of cementum after gingival recession, resulting in exposure of cervical dentine and patency of dentinal tubules. The effect of thermally cooled pulsed neodymium:yttrium-aluminium-garnet (Nd:YAG) laser on the permeability and structural appearance of the root canal wall was investigated in vitro. The aim of this study was to compare the occluding effect of Nd:YAG laser with that of sensodyne on exposed dentine.
  
  
  METHODS
  Forty freshly extracted human maxillary anterior teeth were collected at random. Root canal obturations were performed using master apical file no. 60 k-type for obturated teeth. All teeth were stored in 100% humidity at 37 degrees C for 48h to allow time for the sealer to set. Dentine of 35 teeth was exposed by removing the cementum, and the remaining five teeth represented a negative control group. Specimens were examined using stereomicroscopy to show the surface topography of the dentine substrate before and after treatment with Nd:YAG laser or sensodyne.
  
  
  RESULTS
  A double-blind technique was used when taking measurements of ink penetration (in mm) for each group. Teeth treated by Nd:YAG laser showed the least ink penetration, followed by teeth treated by sensodyne. The positive control group demonstrated complete ink penetration and the negative control group showed no ink penetration. Stereomicroscopic examination of specimens treated with Nd:YAG laser showed deposition on the dentinal surface, and specimens treated with sensodyne showed partial deposition. Untreated specimens were free of deposition and the tubules remained patent.
  
  
  CONCLUSIONS
  There is no significant difference in the occluding effect of Nd:YAG laser and sensodyne toothpaste. Both treatments have a promising effect on the reduction of permeation through exposed dentinal tubules. However, the occluding effect of Nd:YAG laser occurs within seconds whereas that of sensodyne takes at least 3 weeks.
authors.affiliation: Department of Oral Pathology, College of Dentistry, University of Baghdad, Baghdad, Iraq. lehadhm@yahoo.co.uk
authors.forename: Lehadh M
authors.initials: LM
authors.lastname: Al-Azzawi
authors.forename: Raad N
authors.initials: RN
authors.lastname: Dayem
mesh_terms: D000704:Analysis of Variance; D003804:Dentin / Q000187:drug effects / Q000528:radiation effects / Q000648:ultrastructure; D004338:Drug Combinations; D005459:Fluorides / Q000627:therapeutic use*; D006801:Humans; D028022:Low-Level Light Therapy / Q000379:methods*; D008855:Microscopy, Electron, Scanning; D009566:Nitrates / Q000627:therapeutic use*; D010539:Permeability; D010710:Phosphates / Q000627:therapeutic use*; D019553:Tooth, Nonvital / Q000188:drug therapy / Q000532:radiotherapy; D014100:Toothpastes / Q000627:therapeutic use*
chemical_list: D004338:Drug Combinations; D009566:Nitrates; D010710:Phosphates; C097427:Sensodyne; D014100:Toothpastes; D005459:Fluorides