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Evaluation of bond strength after dentin pretreatment with hydroxyapatite nanoparticles, antimicrobial effect and cytotoxicity of a silver nanoparticle-modified adhesive


The aim of this study is to evaluate the bonding interface produced by a silver nanoparticle (NAg) modified adhesive system used after pretreatment of dentin with hydroxyapatite nanoparticles (NHA), in order to integrate the antibacterial effects (Nag) and collagen protection (NHA), which will be evidenced by immediate and after storage (6 months) microtensile bond strength. Besides, it will also be evaluated antimicrobial effect and cytotoxicity of the NAg-modified adhesive system. The NAg and NHA nanoparticles will be synthesized and characterized by scanning electron microscopy (SEM), x-ray dispersion spectroscopy (EDX), x-ray diffractometry, transmission electron microscopy (TEM) and atomic force microscopy (AFM). NAg (0.05% or 0.1%) will be incorporated into the primer and bonding agents of Scotchbond Multi-Purpose (SBMP). 100 human teeth will be used: SBMP (control); SBMP with NAg (0.05% or 0.1%); Pre treatment with NHA (0.05% or 0.1%) + SBMP; Pretreatment with NHA (0.05% or 0.1%) + SBMP with NAg (0.05% or 0.1%). The mechanical properties of the adhesive interface will be measured by microtensile bond strength: immediate (24 hours) and after 6 months of storage in distilled water. The adhesive interface (n = 2) will be analyzed by scanning electron microscopy (SEM) and confocal raman microscopy (MCR). The antimicrobial effect will be evaluated by culture methods: live / dead assay, MTT assay and by molecular method that associates the real-time polymerase chain reaction (q-PCR) with propionic monoazide (PMA). The cytotoxicity of the experimental groups of the adhesives modified by NAg will be measured by contact with stem cells of the dental pulp and compared to the SBMP control (AU)