Synthesis of zirconia, organic and hybrid nanofibers for reinforcement of polymethyl methacrylate denture base: evaluation of flexural strength and modulus, fracture toughness and impact strength

Abstract

Objective The objective of this study was to synthesize and characterize inorganic zirconium oxide (ZrO2), organic [bisphenol A diglycidyl ether dimethacrylate (Bis-GMA)+triethylene glycol dimethacrylate (TEGDMA)+polyethylene glycol dimethacrylate (PEGDMA)] and hybrid (ZrO2+ Bis-GMA + TEGDMA) nanofibers and the use of these nanofibers for improving flexural strength (FS) and flexural modulus (FM), fracture toughness (FT) and impact strength (IS) of polymethyl methacrylate (PMMA) resin. Materials and methods Inorganic, organic and hybrid nanofibers were synthesized by wet electrospinning technique. The study was divided into four groups according to the type of added nanofibers (6%) to the heat-curing PMMA denture base resin; control group: PMMA without nanofibers, inorganic group: PMMA with silanized ZrO2 nanofibers, organic group: PMMA with Bis-GMA/TEGDMA/PEGDMA nanofibers and hybrid group: PMMA with ZrO2/Bis-GMA/TEGDMA nanofibers. According to ISO FDIS 20795-1:2013, three-point bending test was used to measure FS, FM and FT for each group (n = 10). According to ISO 197-A1: 2005, impact tester was used to measure IS for each group (n = 10). One-way analysis of variance was used for statistical significance between groups and post-hoc (Tukey's test) was used for multiple comparisons. P value less than or equal to 0.01 was considered significantly different. Results The synthesized pure forms of three types of nanofibers were characterized by scanning electron microscope and Fourier transform infrared spectroscopy. Nanofibers-reinforced groups (ZrO2, hybrid and organic, respectively) recorded high means % than that of the control group as follows: 205, 184 and 170% for FS (MPa), 184, 149 and 120% for FM (GPa), 210, 189 and 177% for FT (MPa m1/2) and 151, 180 and 176% for IS (KJ/m2). In each of the four tested mechanical properties, one-way analysis of variance revealed a significant differences between the studied groups (P = 0.000) and post-hoc (Tukey's test) revealed that nanofibers-reinforced groups were markedly significantly higher than control group (P = 0.000). Conclusion ZrO2, Bis-GMA/TEGDMA/PTEGDMA and ZrO2/Bis-GM/TEGDMA hybrid nanofibers synthesized by electrospinning technique improved significantly FS, FM, FT and IS of PMMA resin (P = 000).