Mechanical Properties of Nanohybrid Resin Composites Containing Various Mass Fractions of Modified Zirconia Particles

Abstract

Gaoying Hong,1 Jiaxue Yang,1 Xin Jin,2 Tong Wu,1 Shiqi Dai,1 Haifeng Xie,1 Chen Chen2 1Jiangsu Key Laboratory of Oral Diseases, Department of Prosthodontics, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing, People’s Republic of China; 2Jiangsu Key Laboratory of Oral Diseases, Department of Endodontics, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing, People’s Republic of ChinaCorrespondence: Chen Chen; Haifeng Xie Han-Zhong Road 136thAffiliated Hospital of Stomatology, Nanjing Medical University, Nanjing 210029, People’s Republic of ChinaTel [phone]; [phone]Fax [phone]Email [email protected]; [email protected]: The aim of this study was to investigate the effect of various mass fractions of 10-methacry-loyloxydecyl dihydrogen phosphate (MDP)-conditioned or unconditioned zirconia nano- or micro-particles with different initiator systems on the mechanical properties of nanohybrid resin composites.Methods: Both light-cured (L) and dual-cured (D) resin composites were prepared. When the mass fraction of the nano- or micro-zirconia fillers reached 55 wt%, resin composites were equipped with dual-cured initiator systems. We measured the three-point bending-strength, elastic modulus, Weibull modulus and translucency parameter of the nanohybrid resin composites containing various mass fractions of MDP-conditioned or unconditioned zirconia nano- or micro-particles (0%, 5 wt%, 10 wt%, 20 wt%, 30 wt% and 55 wt%). A Cell Counting Kit (CCK)-8 was used to test the cell cytotoxicity of the experimental resin composites. The zirconia nano- or micro-particles with MDP-conditioning or not were characterized by transmission electron microscopy (TEM), Fourier infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS).Results: Resin composites containing 5– 20 wt% MDP-conditioned or unconditioned nano-zirconia fillers exhibited better three-point bending-strength than the control group without zirconia fillers. Nano- or micro-zirconia fillers decreased the translucence of the nanohybrid resin composites. According to the cytotoxicity classification, all of the nano- or micro-zirconia fillers containing experimental resin composites were considered to have no significant cell cytotoxicity. The FTIR spectra of the conditioned nano- or micro-fillers showed new absorption bands at 1719 cm− 1 and 1637 cm− 1, indicating the successful combination of MDP and zirconia particles. The XPS analysis measured Zr–O–P peak area on MDP-conditioned nano- and micro-zirconia fillers at 39.91% and 34.89%, respectively.Conclusion: Nano-zirconia filler improved the mechanical properties of nanohybrid resin composites, but cannot be the main filler to replace silica filler. The experimental dual-cured composites can be resin cements with better opacity effects and a low viscosity.Keywords: resin composite, nano-zirconia filler, MDP, initiator system, mechanical property, translucence

Keywords

• resin composite
• nano-zirconia filler
• mdp
• initiator system
• mechanical property
• translucence