title: Effects of Er:YAG and Nd:YAG lasers on dentin permeability in root surfaces: a preliminary in vitro study.
abstract: OBJECTIVE
  This in vitro study evaluated the effects of Nd:YAG and Er:YAG lasers on reducing dentin permeability by sealing opened tubules.
  
  
  BACKGROUND
  According to hydrodynamic theory, dentine hypersensitivity occurs when dentin is exposed with tubules opened. Consequently, a painful sensation occurs due to an intensification of the dentinal permeability. Treatment, therefore, should be based on a decrease of this permeability, achieved by the obliteration of dentinal tubules. The Nd:YAG laser is known for its capacity to seal dentinal tubules; however, few studies concerning treatment with Er:YAG laser are available.
  
  
  METHODS
  The Nd:YAG laser was used, based on two parameters: (A) 1.0 W, 10 Hz, and (B) 1.5 W, 15 Hz. The Er:YAG laser was used at 60 mJ, 2 Hz, four applications of 20 sec each, at 6 mm from the surface. After irradiation, all samples were immersed in 1% Rodamine B dye solution, in order to evaluate the penetration of the dye solution and observe the decrease/increase of dentinal permeability after the laser treatment.
  
  
  RESULTS
  The laser conditions used in the present study decreased the permeability as follows: (a) when using the Er:YAG laser at 60 mJ, 2 Hz in 26.05%, and (b) when using the Nd:YAG laser at 1.5 W, 15 Hz in 19.03%--with no statistical difference between them. Additionally, the Nd:YAG laser at 1.0 W, 10 Hz, decreased permeability in 4.59%, with a smaller effect.
  
  
  CONCLUSIONS
  According to the results of this in vitro study, the Er:YAG laser at 60 mJ, 2 Hz, and the Nd:YAG laser at 1.5 W, 15 Hz are useful for decreasing dentin permeability.
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, University of São Paulo, São Paulo, Brazil.
authors.forename: Ana Cecília Corrêa
authors.initials: AC
authors.lastname: Aranha
authors.forename: Fernanda Baudichon
authors.initials: FB
authors.lastname: Domingues
authors.forename: Vanessa Ormeni
authors.initials: VO
authors.lastname: Franco
authors.forename: Norbert
authors.initials: N
authors.lastname: Gutknecht
authors.forename: Carlos de Paula
authors.initials: Cde P
authors.lastname: Eduardo
mesh_terms: D000704:Analysis of Variance; D003786:Dental Pulp Cavity / Q000528:radiation effects*; D003806:Dentin Permeability / Q000528:radiation effects*; D003807:Dentin Sensitivity / Q000517:prevention & control; D004871:Erbium; D005069:Evaluation Studies as Topic; D006801:Humans; D066298:In Vitro Techniques; D053685:Laser Therapy; D008963:Molar / Q000528:radiation effects; D009354:Neodymium; D011336:Probability; D012016:Reference Values; D012390:Root Canal Therapy / Q000295:instrumentation* / Q000379:methods; D012494:Sampling Studies; D012680:Sensitivity and Specificity
chemical_list: D009354:Neodymium; D004871:Erbium