Dental Resin Composites Reinforced with Short S-Glass Fibers and Nanodiamonds

Abstract

<p><strong>Objectives</strong>: This study aimed to develop a novel bisphenol A (BPA) free dental resin composite using fluorinated UDMA (FUDMA) and micro/nano fillers containing glass particles, short S-glass fibers, and nanodiamonds for dental restoration applications. The resin/filler ratio was optimized to enhance the mechanical and physical properties of the composites with improved aesthetics.<br><strong>Methods</strong>: The resin system consisted of FUDMA/TEGDMA containing 5-10 wt% short S-glass fibers, 0.2 wt% nanodiamonds, and 45-55 wt% glass particles (Diameter: ~ 0.7 µm). Short S-glass fibers were treated with a selective metal etching method in 10-98% sulfuric acid for 1-3 hours under various acidic conditions, followed by grafting of silane coupling agent (8-MOTS) with different concentrations to maximize the fiber/polymer interfacial bond strength. All raw materials were mixed in a high-speed mixer under dark conditions to prevent pre-polymerization. After photocuring (<em>λ</em>: ~450 nm) for 1 minute, the mechanical and physical properties were investigated, namely: 3-point bend test and micro-indentation, and digital shade measurement (CIE76).<br><strong>Results</strong>: Short S-glass fibers exhibited the best surface condition when treated in 10% sulfuric acid etch for 3 hours followed by 1% 8-MOTS silanization. This treatment provided a thin nano-coating for effective adhesion of the fibers and resin. The composites reinforced with 10 wt% glass fibers increased the flexural strength and modulus by up to 54.42% and 21.82%, respectively, compared to the composites with 5 wt%. The addition of 0.2 wt% nanodiamonds to the composites significantly increased the hardness (p<0.01) and resulted in a smaller color difference (CIE <em>delta-E</em>: 17.95) from the standard white point compared to the composites without nanodiamonds (<em>delta-E</em>: 28.90).<br><strong>Conclusions</strong>: This research has successfully developed BPA-free dental resin composites using surface modified glass fibers and nanodiamonds resulting in improved mechanical properties and aesthetics. The improved surface hardness and aesthetic appeal can offer promising potential for esthetically demanding restorations.<br></p>