Síntese e caracterização de nanopartículas de vidro bioativo contendo flúor e avaliação in vitro do potencial para aplicação no tratamento da hipersensibilidade dentinária

Abstract

Dentin hypersensitivity is characterized by sharp localized pain, non spontaneous, and occurring in response to some stimulus. This pain is caused by loss of the tooth structure, resulting in exposure of dentinal tubules to the oral environment. Several methods for treating dentin hypersensitivity have been researched; however none of them was completely effective. In the last decades bioactive glass has been used on studies about the specific effects on remineralization of dentin, due to their excellent regenerative properties in mineralized tissues. It is known that the effect of bioactive glass can be enhanced in the nanoscale. The incorporation of Fluor may result in formation of fluorapatite (FAP), which is chemically more stable than hydroxyapatite or carbonated hydroxyapatite, and therefore is of interest for dental applications. The aim of this study was to synthesize and characterize a new system of Fluor containing bioactive glass nanoparticles (BGNPF), and evaluate the potential of remineralization in vitro by occlusion of dentinal tubules of dentin discs. The effect of size and composition of bioactive glasses was analyzed and compared, in order to increase the effectiveness of the treatment of dentin hypersensitivity. As the synthesis of BGNPF by the sol gel route is a pioneer research, previous steps were necessary for the development of this work. Thus, this study initially evaluated bioactive glass particles not containing Fluor, than microparticles of bioactive glass containing different Fluor contents, with and without the use of ultrasound, to finally synthesize and evaluate the Fluor containing bioactive glass nanoparticles. BGNPF were syntetized by sol-gel route and characterized by Scanning Electron Microscopy (SEM), Energy dispersive spectroscopy (EDS), Atomic force microscopy (AFM), X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), Energy dispersive spectroscopy (EDS) and Dynamic Light Scattering (DLS), Brunauer-Emmett-Teller (BET) and X-ray photoelectron spectroscopy (XPS). For the in-vitro study teeth obtained from the bank of teeth from the Dental School of the Federal University of Minas Gerais were used. The dentin samples were demineralized with phosphoric acid 37% and treated for 1, 3, 7 and 14 days with gel containing FBGNP. The gel was characterized by MTT to evaluate its biocompatibility. SEM micrographs showed that the particles are quite uniform spherical nanostructures, occurring agglomeration or partial sinterization of the particulate system after heat treatment. EDS analysis indicated the presence of Fluor in the system, and the results of the various analysis techniques used suggest the formation of fluorapatite crystals embedded within the matrix of the bioactive glass. The gel containing NPVBF presented no citotoxicity and was effective in obliterating the dentinal tubules in vitro, reaching this result after 1 day of application, presenting better results than the pastes already in the markete. Therefore, it is possible to conclude that NPVBF it is a potential material to be used for treatment of dentin hypersensitivity.