title: Zinc-modified nanopolymers improve the quality of resin-dentin bonded interfaces.
abstract: BACKGROUND
  Demineralized collagen fibers at the hybrid layer are susceptible to degradation. Remineralization may aid to improve bond longevity.
  
  
  OBJECTIVE
  The aim of the present study was to infiltrate zinc and calcium-loaded polymeric nanoparticles into demineralized dentin to facilitate hybrid layer remineralization.
  
  
  METHODS
  Zinc or calcium-loaded polymeric nanoparticles were infiltrated into etched dentin, and Single Bond Adhesive was applied. Bond strength was tested after 24 h and 6 months storage. Nanomechanical properties, dye-assisted confocal laser microscopy, and Masson's trichrome staining evaluation were performed to assess for the hybrid layer morphology, permeability, and remineralization ability after 24 h and 3 months. Data were analyzed by ANOVA and Student-Newman-Keuls multiple comparisons tests (p < 0.05).
  
  
  RESULTS
  Immediate bond strength was not affected by nanoparticles infiltration (25 to 30 MPa), while after 6 months, bond strengths were maintained (22 to 24 MPa). After 3 months, permeability occurred only in specimens in which nanoparticles were not infiltrated. Dentin remineralization, at the bottom of the hybrid layer, was observed in all groups. After microscopy analysis, zinc-loaded nanoparticles were shown to facilitate calcium deposition throughout the entire hybrid layer. Young's modulus at the hybrid layer increased from 2.09 to 3.25 GPa after 3 months, in specimens with zinc nanoparticles; meanwhile, these values were reduced from 1.66 to 0.49 GPa, in the control group.
  
  
  CONCLUSIONS
  Infiltration of polymeric nanoparticles into demineralized dentin increased long-term bond strengths. Zinc-loaded nanoparticles facilitate dentin remineralization within the complete resin-dentin interface.
  
  
  CONCLUSIONS
  Resin-dentin bond longevity and dentin remineralization at the hybrid layer were facilitated by zinc-loaded nanoparticles.
authors.affiliation: Dental School, Colegio Maximo, University of Granada, Campus de Cartuja s/n, 18017, Granada, Spain. rosorio@ugr.es.
authors.forename: Raquel
authors.initials: R
authors.lastname: Osorio
authors.affiliation: Dental School, Colegio Maximo, University of Granada, Campus de Cartuja s/n, 18017, Granada, Spain.
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Cabello
authors.affiliation: NanoMyP, Spin-Off Enterprise, University of Granada, Edificio BIC-Granada. Av. Innovación1, Armilla, 18016, Granada, Spain.
authors.forename: Antonio L
authors.initials: AL
authors.lastname: Medina-Castillo
authors.affiliation: Dental School, Colegio Maximo, University of Granada, Campus de Cartuja s/n, 18017, Granada, Spain.
authors.forename: Estrella
authors.initials: E
authors.lastname: Osorio
authors.affiliation: Dental School, Colegio Maximo, University of Granada, Campus de Cartuja s/n, 18017, Granada, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Toledano
mesh_terms: D000134:Acid Etching, Dental; D002118:Calcium / Q000737:chemistry; D001840:Dental Bonding; D003804:Dentin / Q000737:chemistry*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D055119:Elastic Modulus; D006801:Humans; D008422:Materials Testing; D018613:Microscopy, Confocal; D008964:Molar, Third; D053758:Nanoparticles / Q000737:chemistry*; D019279:Resin Cements / Q000737:chemistry*; D013194:Staining and Labeling; D013499:Surface Properties; D013718:Tensile Strength; D014089:Tooth Remineralization; D015032:Zinc / Q000737:chemistry*
chemical_list: D017220:Dentin-Bonding Agents; D019279:Resin Cements; D015032:Zinc; D002118:Calcium
keywords: Adhesives; Dentin; Hybrid layer; Nanopolymers; Remineralization; Zinc
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