title: Influence of Nd:YAG laser on the bond strength of self-etching and conventional adhesive systems to dental hard tissues.
abstract: OBJECTIVE
  The aim of this study was to investigate the influence of Nd:YAG laser on the shear bond strength to enamel and dentin of total and self-etch adhesives when the laser was applied over the adhesives, before they were photopolymerized, in an attempt to create a new bonding layer by dentin-adhesive melting.
  
  
  METHODS
  One-hundred twenty bovine incisors were ground to obtain flat surfaces. Specimens were divided into two substrate groups (n=60): substrate E (enamel) and substrate D (dentin). Each substrate group was subdivided into four groups (n=15), according to the surface treatment accomplished: X (Xeno III self-etching adhesive, control), XL (Xeno III + laser Nd:YAG irradiation at 140 mJ/10 Hz for 60 seconds + photopolymerization, experimental), S (acid etching + Single Bond conventional adhesive, Control), and SL (acid etching + Single Bond + laser Nd:YAG at 140 mJ/10 Hz for 60 seconds + photopolymerization, experimental). The bonding area was delimited with 3-mm-diameter adhesive tape for the bonding procedures. Cylinders of composite were fabricated on the bonding area using a Teflon matrix. The teeth were stored in water at 37°C/48 h and submitted to shear testing at a crosshead speed of 0.5 mm/min in a universal testing machine. Results were analyzed with three-way analysis of variance (ANOVA; substrate, adhesive, and treatment) and Tukey tests (α=0.05). ANOVA revealed significant differences for the substrate, adhesive system, and type of treatment: lased or unlased (p<0.05). The mean shear bond strength values (MPa) for the enamel groups were X=20.2 ± 5.61, XL=23.6 ± 4.92, S=20.8 ± 4.55, SL=22.1 ± 5.14 and for the dentin groups were X=14.1 ± 7.51, XL=22.2 ± 6.45, S=11.2 ± 5.77, SL=15.9 ± 3.61. For dentin, Xeno III self-etch adhesive showed significantly higher shear bond strength compared with Single Bond total-etch adhesive; Nd:YAG laser irradiation showed significantly higher shear bond strength compared with control (unlased).
  
  
  CONCLUSIONS
  Nd:YAG laser application prior to photopolymerization of adhesive systems significantly increased the bond strength to dentin.
authors.affiliation: Department of Restorative Dentistry, São José dos Campos School of Dentistry, UNESP- Univ Estadual Paulista, São Paulo, Brazil.
authors.forename: A K
authors.initials: AK
authors.lastname: Marimoto
authors.forename: L A
authors.initials: LA
authors.lastname: Cunha
authors.forename: K C K
authors.initials: KC
authors.lastname: Yui
authors.forename: M F R L
authors.initials: MF
authors.lastname: Huhtala
authors.forename: D C
authors.initials: DC
authors.lastname: Barcellos
authors.forename: A
authors.initials: A
authors.lastname: Prakki
authors.forename: S E P
authors.initials: SE
authors.lastname: Gonçalves
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D000818:Animals; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry / Q000528:radiation effects; D002417:Cattle; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003743:Dental Enamel / Q000648:ultrastructure*; D003764:Dental Materials / Q000737:chemistry; D003799:Dental Stress Analysis / Q000295:instrumentation; D003804:Dentin / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry / Q000528:radiation effects*; D053844:Lasers, Solid-State; D055115:Light-Curing of Dental Adhesives / Q000295:instrumentation / Q000379:methods; D008422:Materials Testing; D010756:Phosphoric Acids / Q000737:chemistry; D058105:Polymerization; D011829:Radiation Dosage; D033081:Shear Strength; D013314:Stress, Mechanical; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D003188:Composite Resins; D003764:Dental Materials; D017220:Dentin-Bonding Agents; C444701:Filtek Z250; D010756:Phosphoric Acids; C487957:Xeno III; C115612:single bond; D014867:Water; D017438:Bisphenol A-Glycidyl Methacrylate; C030242:phosphoric acid