Polymeric nanoparticles protect the resin-dentin bonded interface from cariogenic biofilm degradation

• Published in: Acta biomaterialia 2020-07, Vol.111, p.316-326
• Main Authors: Toledano-Osorio, Manuel, Osorio, Raquel, Aguilera, Fátima S, Medina-Castillo, Antonio Luis, Toledano, Manuel, Osorio, Estrella, Acosta, Sergio, Chen, Ruoqiong, Aparicio, Conrado
• Format: Article
• Language: English
• Subjects: Antiinfectives and antibacterials; Bacteria; Biodegradation; Biofilm; Biofilms; Collagen; Degradation; Dental Bonding; Dentin; Dentin-Bonding Agents - pharmacology; Disks; Doxycycline; Electron microscopy; Emission analysis; Etching; Field emission microscopy; Field emission spectroscopy; Interface; Interfaces; Materials Testing; Mineralization; Nanoparticle; Nanoparticles; Polymers; Raman spectroscopy; Remineralization; Resin Cements - pharmacology; Resins; Tensile Strength; Zinc
• ISSN: 1742-7061; 1878-7568
• DOI: 10.1016/j.actbio.2020.05.002

The objective was to assess doxycycline (Dox) and zinc (Zn) doped nanoparticles' (NPs) potential to protect the resin-dentin interface from cariogenic biofilm. Three groups of polymeric NPs were tested: unloaded, loaded with zinc and with doxycycline. NPs were applied after dentin etching. The disks were exposed to a cariogenic biofilm challenge in a Drip-Flow Reactor during 72 h and 7 d. Half of the specimens were not subjected to biofilm formation but stored 72 h and 7 d. LIVE/DEAD® viability assay, nano-dynamic mechanical assessment, Raman spectroscopy and field emission electron microscopy (FESEM) analysis were performed. The measured bacterial death rates, at 7 d were 46% for the control group, 51% for the undoped-NPs, 32% for Dox-NPs, and 87% for Zn-NPs; being total detected bacteria reduced five times in the Dox-NPs group. Zn-NPs treated samples reached, in general, the highest complex modulus values at the resin-dentin interface over time. Regarding the mineral content, Zn-NPs-treated dentin interfaces showed the highest mineralization degree associated to the phosphate peak and the relative mineral concentration. FESEM images after Zn-NPs application permitted to observe remineralization of the etched and non-resin infiltrated collagen layer, and bacteria were scarcely encountered. The combined antibacterial and remineralizing effects, when Zn-NPs were applied, reduced biofilm formation. Dox-NPs exerted an antibacterial role but did not remineralize the bonded interface. Undoped-NPs did not improve the properties of the interfaces. Application of Zn-doped NPs during the bonding procedure is encouraged. Application of Zn-doped nanoparticles on acid etched dentin reduced biofilm formation and viability at the resin-dentin interface due to both remineralization and antibacterial properties. Doxycycline-doped nanoparticles also diminished oral biofilm viability, but did not remineralize the resin-dentin interface. [Display omitted]