title: Microtensile bond strength of resin composite to dentin treated with Er:YAG laser of bleached teeth.
abstract: The objective of this study was to evaluate the influence of Er:YAG laser (λ = 2.94 μm) on microtensile bond strength (μTBS) and superficial morphology of bovine dentin bleached with 16% carbamide peroxide. Forty bovine teeth blocks (7 × 3 × 3 mm(3)) were randomly assigned to four groups: G1- bleaching and Er:YAG irradiation with energy density of 25.56 J/cm(2) (focused mode); G2 - bleaching; G3 - no-bleaching and Er:YAG irradiation (25.56 J/cm(2)); G4 - control, non-treated. G1 and G2 were bleached with 16% carbamide peroxide for 6 h during 21 days. Afterwards, all blocks were abraded with 320 to 600-grit abrasive papers to obtain flat standardized dentin surfaces. G1 and G3 were Er:YAG irradiated. Blocks were immediately restored with 4-mm-high composite resin (Adper Single Bond 2, Z-250-3 M/ESPE). After 24 h, the restored blocks (n = 9) were serially sectioned and trimmed to an hour-glass shape of approximately 1 mm(2) at the bonded interface area, and tested in tension in a universal testing machine (1 mm/ min). Failure mode was determined at a magnification of 100× using a stereomicroscope. One block of each group was selected for scanning electron microscope (SEM) analysis. μTBS data was analyzed by two-way ANOVA and Tukey test (α = 0.05). Mean bond strengths (SD) in MPa were: G1- 32.7 (5.9)(A); G2- 31.1 (6.3)(A); G3- 25.2 (8.3)(B); G4- 36.7 (9.9).(A) Groups with different uppercase letters were significantly different from each other (p < .05). Enamel bleaching procedure did not affect μTBS values for dentin adhesion. Er:YAG laser irradiation with 25.56 J/cm(2) prior to adhesive procedure of bleached teeth did not affect μTBS at dentin and promoted a dentin surface with no smear layer and opened dentin tubules observed under SEM. On the other hand, Er:YAG laser irradiation prior to adhesive procedure of non-bleached surface impaired μTBS compared to the control group.
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, Guarulhos University, Praça Teresa Cristina, Guarulhos, SP, Brazil.
authors.forename: Eduardo dos Santos
authors.initials: Edos S
authors.lastname: Leonetti
authors.forename: José Augusto
authors.initials: JA
authors.lastname: Rodrigues
authors.forename: André Figueiredo
authors.initials: AF
authors.lastname: Reis
authors.forename: Ricardo Scarparo
authors.initials: RS
authors.lastname: Navarro
authors.forename: Ana Cecília Correa
authors.initials: AC
authors.lastname: Aranha
authors.forename: Alessandra
authors.initials: A
authors.lastname: Cassoni
mesh_terms: D000818:Animals; D000077463:Carbamide Peroxide; D002417:Cattle; D003188:Composite Resins / Q000528:radiation effects*; D001840:Dental Bonding; D003743:Dental Enamel / Q000187:drug effects / Q000528:radiation effects; D003804:Dentin / Q000528:radiation effects* / Q000648:ultrastructure; D053844:Lasers, Solid-State; D008855:Microscopy, Electron, Scanning; D010545:Peroxides / Q000494:pharmacology; D019279:Resin Cements / Q000528:radiation effects; D013718:Tensile Strength; D014073:Tooth Bleaching; D014508:Urea / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D003188:Composite Resins; D010545:Peroxides; D019279:Resin Cements; D000077463:Carbamide Peroxide; D014508:Urea