title: Analysis of the interfacial micromorphology and bond strength of adhesive systems to Er:YAG laser-irradiated dentin.
abstract: This study evaluated the effects of different parameters of dentin irradiation with erbium -doped yttrium aluminum garnet (Er:YAG) laser on bond strength to dentin and analyzed the ultramorphological characteristics of resin-laser-irradiated dentin interfaces using a transmission electron microscope (TEM). Dentin surfaces were abraded with SiC paper (600 grit) or Er:YAG laser-irradiated (120/4, 140/6, 180/4, or 200/6 mJ/Hz). Three adhesive systems were tested: Single Bond Plus (3M ESPE), Clearfil Protect Bond (Kuraray Med.), and Clearfil Tri-S Bond (Kuraray Med.). Treatments were performed over flat dentin surfaces of human third molars. Specimens were stored in distilled water for 1 week or 6 months and prepared for a microtensile bond strength test and interfacial ultrastructure for analysis. Microtensile bond strength data (n = 5) were analyzed with three-way analysis of variance. Irradiation with Er:YAG laser did not reduce the bond strength values for self-etching adhesives even after 6 months of water storage. The hybrid layer formation was observed only when the adhesives were applied to non-irradiated dentin (control group). Nanoleakage occurred in all resin-dentin interfaces using Single Bond Plus for both periods. Nanoleakage pattern and bond strength of self-etching adhesives to dentin were less affected by Er:YAG laser irradiation and by the 6-month storage in water than was those of the etch-and-rinse adhesive. TEM analysis revealed no hybridization when dentin was laser-irradiated.
  
  
  CONCLUSIONS
  Minimally invasive caries removal has been proposed. Nevertheless, bonding mechanisms to lased dentin are not entirely described. Knowing the interaction between the treated dentin and bonding agents and its behavior over time is of utmost importance for new technologies. Regarding that, two-bottle self-etching adhesive system provided a more consistent evidence of its better behavior when bonding to lased substrate.
authors.affiliation: Department of Biophotonics Applied to Health Sciences, Nove de Julho University, São Paulo, SP, Brazil.
authors.forename: Marcelo Tavares
authors.initials: MT
authors.lastname: de Oliveira
authors.forename: André Figueiredo
authors.initials: AF
authors.lastname: Reis
authors.forename: Cesar Augusto Galvão
authors.initials: CA
authors.lastname: Arrais
authors.forename: Andrea Nóbrega
authors.initials: AN
authors.lastname: Cavalcanti
authors.forename: Ana Cecília Corrêa
authors.initials: AC
authors.lastname: Aranha
authors.forename: Carlos
authors.initials: C
authors.lastname: de Paula Eduardo
authors.forename: Marcelo
authors.initials: M
authors.lastname: Giannini
mesh_terms: D003738:Dental Cements / Q000627:therapeutic use; D045662:Dental Etching / Q000379:methods; D003804:Dentin / Q000528:radiation effects* / Q000648:ultrastructure; D006801:Humans; D053844:Lasers, Solid-State / Q000627:therapeutic use*; D055115:Light-Curing of Dental Adhesives / Q000379:methods*; D046529:Microscopy, Electron, Transmission; D012117:Resins, Synthetic / Q000627:therapeutic use; D013499:Surface Properties; D013718:Tensile Strength; D013997:Time Factors
chemical_list: D003738:Dental Cements; D012117:Resins, Synthetic