ABSTRACT

Objective: To investigate the mechanical properties of various mass fractions of Nylon 6 (N6), polymethyl-metacrylate (PMMA) and polyvinylidene-difluoride (PVDF) nanofibres reinforced bisphenol A-glycidyl methacrylate (Bis-GMA) and tri-ethylene glycol dimethacrylate (TEGDMA) based dental composite resins and to evaluate the penetration characteristics of the nanofibres into the resin.

Methods: Nylon 6, PMMA and PVDF nanofibres were produced using the electrospinning method. The morphologies of the fabricated nanofibres were evaluated with a scanning electron microscope (SEM). The nanofibres were placed into the resin matrix at different mass fractions (3%, 5% and 7%). The three-point bending test was applied to nanofibre-reinforced dental composite resins and neat resin specimens. The flexural strength (Fs), flexural modulus (EY) and work of fracture (WOF) of the groups were found. The analysis of variance was used for the statistical analysis of the acquired data. Tukey’s multiple test was performed to compare the Fs, EY and WOF means. Fractured surfaces of the samples were observed by SEM, and fracture morphologies were evaluated.

Results: Polymethyl-metacrylate nanofibres dissolved in the matrix, and a polymer alloy took place in the matrix. Fibre pull-out and fibre bridging mechanisms were observed by SEM images of the N6 and PVDF nanofibre-reinforced dental composites. The produced nanofibres enhanced the mechanical properties of the dental composite resins.

Conclusion: Fibre pull-out and fibre bridging mechanisms on the fractured surfaces of samples may play a key role in the reinforcement of dental composite resins. However, polymer alloy of PMMA nanofibres increased the mechanical properties of the resin matrix.