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Advisory Committee Chair

John O Burgess

Advisory Committee Members

Amjad Javed

Deniz Cakir-Ustun

Jack E Lemons

Vinoy Thomas

Document Type

Thesis

Date of Award

2012

Degree Name by School

Master of Science in Dentistry (MScD) School of Dentistry

Abstract

Dental composites are used for a variety of applications in dentistry today. Dental composites are composed of a resin matrix containing a blend of Bis-GMA (bis-phenol A-glycidyldimethacrylate) or urethane dimethacrylate (UDMA) along with TEGDMA (tetraethylglycidylmethacrylate). Exhaustive researches has been conducted in recent years to improve physical and mechanical properties of resin-based dental composites, since the existing resin-filler systems may not be suitable for long term applications in large as well as high stress restorations. Nanofillers reinforced composite resins have shown promising results. Silica-based nanoparticles and clusters are blended with larger-sized fillers and are available commercially for restoring large posterior restorations. Unfortunately composites with these nanoparticles, offer poor crack blunting ability due to their shape and small diameters. However, the addition of nanofibers, by virtue of their geometry and large surface/volume ratios, may provide better fracture resistance. So far, there have been a few studies about the nanofibers reinforced dental composites which showed positive results. The objective of this study was to study the effect of silica nanofiber (SNF) and a mixture of Silica filler particles (SFP) reinforcement on the fracture toughness, flexural strength, three body wear, polymerization shrinkage, rheology, and degree of conversion of Bis-GMA/TEGDMA based composite resin. Silica nanofibers (SNF) were fabricated using electrospinning and incorporated, into a bis-GMA/TEGDMA matrix. Experimental groups composed of clear resin and traditionally filled flowable resin (PermaFlo, Ultradent) were tested as negative and positive controls respectively. Data were analyzed using one way ANOVA and Tukey's test. The group with 25 wt% of SNF and SNP mixture demonstrated the highest fracture toughness, flexural strength, wear resistance, and best rheological properties. 35.8wt% showed the lowest polymerization shrinkage and best degree of conversion. Significant increase in all tested properties (p<0.001) was seen after addition of nanofiber.

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