title: In Vitro Study of Dentin Hypersensitivity Treated by 980-nm Diode Laser.
abstract: BACKGROUND
  To investigate the ultrastructural changes of dentin irradiated with 980-nm diode laser under different parameters and to observe the morphological alterations of odontoblasts and pulp tissue to determine the safety parameters of 980-nm diode laser in the treatment of dentin hypersensitivity (DH).
  
  
  METHODS
  Twenty extracted human third molars were selected to prepare dentin discs. Each dentin disc was divided into four areas and was irradiated by 980-nm diode laser under different parameters: Group A: control group, 0 J/cm(2); Group B: 2 W/CW (continuous mode), 166 J/cm(2); Group C: 3W/CW, 250 J/cm(2); and Group D: 4W/CW, 333 J/cm(2). Ten additional extracted human third molars were selected to prepare dentin discs. Each dentin disc was divided into two areas and was irradiated by 980-nm diode laser: Group E: control group, 0 J/cm(2); and Group F: 2.0 W/CW, 166 J/cm(2). The morphological alterations of the dentin surfaces and odontoblasts were examined with scanning electron microscopy (SEM), and the morphological alterations of the dental pulp tissue irradiated by laser were observed with an upright microscope.
  
  
  RESULTS
  The study demonstrated that dentinal tubules can be entirely blocked after irradiation by 980-nm diode laser, regardless of the parameter setting. Diode laser with settings of 2.0 W and 980-nm sealed exposed dentin tubules effectively, and no significant morphological alterations of the pulp and odontoblasts were observed after irradiation.
  
  
  CONCLUSIONS
  Irradiation with 980-nm diode laser could be effective for routine clinical treatment of DH, and 2.0W/CW (166 J/cm(2)) was a suitable energy parameter due to its rapid sealing of the exposed dentin tubules and its safety to the odontoblasts and pulp tissue.
authors.affiliation: Department of Stomatology, Nanfang Hospital, Colleg of Stomatology, Southern Medical University, 510515 Guangzhou, P.R. China. ; These authors contributed equally to this work and should be considered co-first authors.
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Stomatology, Nanfang Hospital, Colleg of Stomatology, Southern Medical University, 510515 Guangzhou, P.R. China. ; These authors contributed equally to this work and should be considered co-first authors.
authors.forename: Jie
authors.initials: J
authors.lastname: Gao
authors.affiliation: Center of Oral Implantology, Guangdong Provincial Stomatological Hospital, Southern Medical University, 510280 Guangzhou, P.R. China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Gao
authors.affiliation: Department of Stomatology, Nanfang Hospital, Colleg of Stomatology, Southern Medical University, 510515 Guangzhou, P.R. China.
authors.forename: Shuaimei
authors.initials: S
authors.lastname: Xu
authors.affiliation: Department of Stomatology, Nanfang Hospital, Colleg of Stomatology, Southern Medical University, 510515 Guangzhou, P.R. China.
authors.forename: Xueling
authors.initials: X
authors.lastname: Zhan
authors.affiliation: Department of Stomatology, Nanfang Hospital, Colleg of Stomatology, Southern Medical University, 510515 Guangzhou, P.R. China.
authors.forename: Buling
authors.initials: B
authors.lastname: Wu
keywords: dentin sensitivity; lasers; scanning electron microscopy