title: In vitro evaluation of dentin tubule occlusion by Denshield and Neodymium-doped yttrium-aluminum-garnet laser irradiation.
abstract: BACKGROUND
  This in vitro study evaluated the efficacy of bioglass (Denshield; Novamin Technology, Alachua, FL) and Neodymium-doped yttrium-aluminum-garnet (Nd:YAG) laser irradiation on dentinal tubuli orifice occlusion (DOO) by comparing samples examined under environmental scanning electron microscope (ESEM) after applying each desensitizing approach separately and in combination.
  
  
  METHODS
  Forty-eight human molars were collected, randomly organized in 4 equal groups, and had their cervical dentin exposed. Additionally, in half of the specimens of each experimental group, the smear layer was removed (subgroups A1, B1, C1, and D1). Group A received NovaMin paste treatment for 5 minutes (NM) to the experimental surface. Group B received Nd:YAG laser irradiation (0.5 w, 10 Hz, and 50 mJ) (L). Group C received NM followed by L. Group D was treated with L followed by NM. All specimens were stored for 24 hours and evaluated for DOO under ESEM by 4 blinded observers.
  
  
  RESULTS
  The presence of a smear layer significantly contributed to DOO regardless of the treatment modality (ordinal logistic regression, P < .001). Compared with group A, all other treatments delivered significantly more occluded dentin orifices (P < .001 for groups B and D and P < .05 for group C). A layer formation was observed in subgroups C2 and D2.
  
  
  CONCLUSIONS
  Under these experimental conditions, a smear layer was essential for successful DOO. Laser irradiation alone and combined with NovaMin proved superior to NovaMin alone on DOO. This combined approach has the potential to improve the outcome of treatment for cervical dentin hypersensitivity. The biological significance of this newly formed layer needs to be elucidated.
authors.affiliation: Department of Endodontics, Dental School, University of Athens, Athens, Greece. elefarm@dent.uoa.gr
authors.forename: Eleftherios-Terry R
authors.initials: ET
authors.lastname: Farmakis
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Kozyrakis
authors.forename: Marouan G
authors.initials: MG
authors.lastname: Khabbaz
authors.forename: Ulrich
authors.initials: U
authors.lastname: Schoop
authors.forename: Franziska
authors.initials: F
authors.lastname: Beer
authors.forename: Andreas
authors.initials: A
authors.lastname: Moritz
mesh_terms: D003804:Dentin / Q000187:drug effects / Q000528:radiation effects / Q000648:ultrastructure*; D057133:Dentin Desensitizing Agents / Q000627:therapeutic use*; D003807:Dentin Sensitivity / Q000628:therapy; D005898:Glass; D006801:Humans; D053844:Lasers, Solid-State / Q000627:therapeutic use*; D028022:Low-Level Light Therapy / Q000379:methods*; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D016369:Smear Layer; D013997:Time Factors; D019237:Tooth Cervix / Q000187:drug effects / Q000528:radiation effects / Q000648:ultrastructure
chemical_list: D057133:Dentin Desensitizing Agents; C510984:NovaMin