title: Mechanical loading influences the viscoelastic performance of the resin-carious dentin complex.
abstract: The aim of this study was to evaluate the changes in the mechanical behavior and bonding capability of Zn-doped resin-infiltrated caries-affected dentin interfaces. Dentin surfaces were treated with 37% phosphoric acid (PA) followed by application of a dentin adhesive, single bond (SB) (PA+SB) or by 0.5 M ethylenediaminetetraacetic acid (EDTA) followed by SB (EDTA+SB). ZnO microparticles of 10 wt. % or 2 wt. % ZnCl2was added into SB, resulting in the following groups: PA+SB, PA+SB-ZnO, PA+SB-ZnCl2, EDTA+SB, EDTA+SB-ZnO, EDTA+SB-ZnCl2. Bonded interfaces were stored for 24 h, and tested or submitted to mechanical loading. Microtensile bond strength was assessed. Debonded surfaces were evaluated by scanning electron microscopy and elemental analysis. The hybrid layer, bottom of the hybrid layer, and peritubular and intertubular dentin were evaluated using a nanoindenter. The load/displacement responses were used for the nanodynamic mechanical analysis III to estimate complex modulus, tan delta, loss modulus, and storage modulus. The modulus mapping was obtained by imposing a quasistatic force setpoint to which a sinusoidal force was superimposed. Atomic force microscopy imaging was performed. Load cycling decreased the tan delta at the PA+SB-ZnCl2and EDTA+SB-ZnO interfaces. Tan delta was also diminished at peritubular dentin when PA+SB-ZnO was used, hindering the dissipation of energy throughout these structures. Tan delta increased at the interface after using EDTA+SB-ZnCl2, lowering the energy for recoil or failure. After load cycling, loss moduli at the interface decreased when using ZnCl2as doping agent, increasing the risk of fracture; but when using ZnO, loss moduli was dissimilarly affected if dentin was EDTA-treated. The border between intertubular and peritubular dentin attained the highest discrepancy in values of viscoelastic properties, meaning a risk for cracking and breakdown of the resin-dentin interface. PA used on dentin provoked differences in complex and storage modulus values at the intertubular and peritubular structures, and these differences were higher than when EDTA was employed. In these cases, the long-term performance of the restorative interface will be impaired.
authors.affiliation: Faculty of Dentistry, Dental Materials Section, University of Granada, Colegio Máximo de Cartuja s/n, 18071 Granada, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Toledano
authors.affiliation: Faculty of Dentistry, Dental Materials Section, University of Granada, Colegio Máximo de Cartuja s/n, 18071 Granada, Spain.
authors.forename: Raquel
authors.initials: R
authors.lastname: Osorio
authors.affiliation: Faculty of Science, Applied Physics Department, University of Granada, Av. Fuente Nueva s/n, 18071 Granada, Spain.
authors.forename: Modesto T
authors.initials: MT
authors.lastname: López-López
authors.affiliation: Faculty of Dentistry, Dental Materials Section, University of Granada, Colegio Máximo de Cartuja s/n, 18071 Granada, Spain.
authors.forename: Fátima S
authors.initials: FS
authors.lastname: Aguilera
authors.affiliation: Bioscience Research Center, College of Dentistry, University of Tennessee, Health Science Center, 875 Union Avenue, Memphis, Tennessee 38163.
authors.forename: Franklin
authors.initials: F
authors.lastname: García-Godoy
authors.affiliation: Faculty of Dentistry, Dental Materials Section, University of Granada, Colegio Máximo de Cartuja s/n, 18071 Granada, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Toledano-Osorio
authors.affiliation: Faculty of Dentistry, Dental Materials Section, University of Granada, Colegio Máximo de Cartuja s/n, 18071 Granada, Spain.
authors.forename: Estrella
authors.initials: E
authors.lastname: Osorio
mesh_terms: D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002712:Chlorides / Q000737:chemistry; D004492:Edetic Acid / Q000737:chemistry; D055119:Elastic Modulus; D006801:Humans; D018625:Microscopy, Atomic Force; D008855:Microscopy, Electron, Scanning; D010756:Phosphoric Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry*; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength; D014783:Viscosity; D017967:Zinc Compounds / Q000737:chemistry; D015034:Zinc Oxide / Q000737:chemistry
chemical_list: D002712:Chlorides; D010756:Phosphoric Acids; D019279:Resin Cements; D017967:Zinc Compounds; C115612:single bond; D017438:Bisphenol A-Glycidyl Methacrylate; C016837:zinc chloride; D004492:Edetic Acid; C030242:phosphoric acid; D015034:Zinc Oxide