Multilayered PMMA Dental Material Reinforced with Electrospun PVP/ZrO2 Composite Nanofiber Fabrics with Enhanced Flexural Properties

This study presents a new design of multilayered PMMA dental composite material combining electrospun continuous composite polyvinylpyrrolidone (PVP) nanofibers filled with zirconia (ZrO2) nanoparticles and two-component self-cure PMMA dental resin. The aim is to improve the mechanical properties of dental PMMA material via the large surface area of electrospun nanofibers, the toughening effect of PVP and ZrO2 nanofillers. First, PVP/ZrO2 composite nanofibers with different ZrO2 contents of 5%, 10% and 20% (wt. % of PVP) were prepared by electrospinning. Then, multilayered samples containing alternating PMMA resin and electrospun composite nanofiber mats with different ZrO2 contents were manufactured by lay-up process. Samples containing single and double layers of nanofiber mats were prepared and cured in a water bath dental acrylic curing device in order to prepare composites without any void. FTIR and SEM results reveal that PVP enables good interfacial interactions and compatibility between the nanofibers and PMMA matrix. The mechanical properties are improved as an increase of the flexural strength up to 83% and 67% is observed for PMMA/PVP/ZrO2-10s and PMMA/PVP/ZrO2-20d samples, respectively. The presence of PVP nanofiber layers significantly improves the flexural toughness, especially for samples reinforced with a single layer of nanofibers where improvements up to 169% and 153% are observed for PMMA/PVP/ZrO2-5s and PMMA/PVP/ZrO2-10s composite samples respectively. The micro-hardness is also higher for composite samples compared to neat PMMA dental material. The overall results clearly depict a noticeable enhancement of the mechanical properties, especially the flexural toughness of PMMA dental material