title: Assessing microleakage on class V composite resin restorations after Er:YAG laser preparation varying the adhesive systems.
abstract: OBJECTIVE
  The aim of this study was to assess the performance of three bonding agents in preventing microleakage of class V cavities prepared and treated by Er:YAG laser associating with acid etching.
  
  
  BACKGROUND
  There has been very little research comparing the efficiency of single-component and self-etching adhesive systems in preventing microleakage of cavities prepared and conditioned with Er:YAG laser.
  
  
  METHODS
  Thirty cavities - with occlusal margin in enamel and cervical in dentin/cementum - were prepared in sound human third molars using a short pulsed Er:YAG laser (500 mJ/5 Hz) The enamel and dentin surfaces were conditioned for 30 sec using lower dosimetries (120 mJ/4 Hz), and the samples were randomly assigned into three groups, according to the adhesive system: (I) Bond-1; (II) Prime & Bond NT; and (III) Etch & Prime 3.0. Groups I and II were acid-etched for 15 sec, and group III did not receive any acid treatment once a self-etching system was employed. Cavities were restored with a light-cured composite resin (JEK-Z250 Filtek-250), and after finishing, the samples were thermocycled, isolated with epoxy resin and nail varnish, immersed in a 0.2% Rhodamine B solution for 24 h, and sectioned longitudinally. The sections obtained were analyzed for leakage using an optical microscope connected to a computer and a video camera. We digitized the images using a special software program that allowed a quantitative evaluation of microleakage in millimeters.
  
  
  RESULTS
  Statistical analysis using the Kruskal-Wallis test showed statistically significant difference between both margins, and the occlusal region presented better marginal sealing. Comparing the three resin bonding systems, Prime & Bond NT entirely sealed both margins, while Etch & Prime 3.0 provided the poorest overall results, showing a statistically significant difference (p < 0.01).
  
  
  CONCLUSIONS
  It may be concluded that, for all the tested materials, microleakage values were higher in cervical (dentin/cementum) margins. Additionally, Prime & Bond NT provided a complete elimination of marginal infiltration at both margins, after treating the dental surface with laser irradiation associated with a sequent acid-etching.
authors.affiliation: Ribeirão Preto School of Dentistry, University of São Paulo, São Paulo, Brazil. rgpalma@forp.usp.br
authors.forename: Regina Guenka
authors.initials: RG
authors.lastname: Palma Dibb
authors.forename: Silmara Aparecida
authors.initials: SA
authors.lastname: Milori Corona
authors.forename: Maria Cristina
authors.initials: MC
authors.lastname: Borsatto
authors.forename: Karen Cristina
authors.initials: KC
authors.lastname: Ferreira
authors.forename: Renata
authors.initials: R
authors.lastname: Pereira Ramos
authors.forename: Jesus
authors.initials: J
authors.lastname: Djalma Pécora
mesh_terms: D003743:Dental Enamel; D003804:Dentin; D006801:Humans; D053685:Laser Therapy