Effects of the reinforced cellulose nanocrystals on glass-ionomer cements

Objective. Glass-ionomer cements (GICs) modified with cellulose nanocrystals (CNs) were characterized and evaluated for compressive strength (CS), diametral tensile strength (DTS) and fluoride release (F-). Methods. Commercially available GICs (Maxxion, Vidrion R, Vitro Molar, Ketac Molar Easy Mix and Fuji Gold Label 9) were reinforced with CNs (0.2% by weight). The microstructure of CNs and of CN-modified GICs were evaluated by transmission electron microscopy (TEM) and by scanning electron microscopy (SEM) while chemical characterization was by Fourier transform infrared spectroscopy (FTIR). Ten specimens each of the unmodified (control) and CN- modified materials (test materials) were prepared for CS and DTS testing. For the fluoride release evaluation, separate specimens (n = 10) of each test and control material were made. The results obtained were submitted to the t-test (p <0.05). Results. The CN reinforcement significantly improved the mechanical properties and significantly increased the F- release of all GICs (p < 0.05). The GICs with CNs showed a fibrillar aggregate of nanoparticles interspersed in the matrix. The compounds with CNs showed a higher amount of C compared to the controls due to the organic nature of the CNs. It was not possible to identify by FTIR any chemical bond difference in the compounds formed when nanofibers were inserted in the GICs. Significance. Modification of GICs with CNs appears to produce promising restorative materials. (C) 2019 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.