Nano Material Reinforced Dental Resin Based Composites

â—†Part 1 Surface modification of nano materialsâ—†Experiment 1 Surface modification and microstructure of nano TiO₂ particles for dental resin based composites (RBCs)â—†Objective: Nano TiO₂ particles were modified by organosilanes to improve their application in dental resin based composites (RBCs).â—†Methods: Nano TiO₂ particles were dispersed in absolute ethanol containing organosilanes by ultrasonic, centrifuged the solution, washed the deposition was by absolute ethanol and centrifuged for three times, the solution was dried to get nano-particles. Fourier transform infrared spectroscopy (FTIR) and Transmission electron microscope (TEM) were used to analyze the modification results. Composite resin specimens with and without nano TiO₂ particles were prepared and examined by TEM.â—†Results: FTIR showed the absorbing bands of cross-linked siloxane network in the modified nano TiO₂ particles. TEM showed no significant changes in configuration and grain size after modification. TEM showed that nano TiO₂ particles were well dispersed in resin matrix among other fillers.â—†Significance: surface modification of nano TiO₂ particles by organosilanes improved the dispersion of these particles in dental RBCs.â—†Key words: dental resin based composites nano TiO₂; organosilanes; surface modification.â—†Experiment 2 Surface modification and microstructure of Single walled carbon nanotubes (SWCNTs) for dental resin based composites (RBCs)â—†Objective: SWCNTs coated by nano SiO₂ were modified by organosilanes to improve their application in dental resin based composites (RBCs).â—†Methods: After refluxed in 3mol/L HNO₃ and oxidised in a mixture of H₂SO₄ and HNO₃, SWCNTs were coated by nano-SiO₂ using sol-gel process, and then were modified by organosilanes; Fourier transform infrared spectroscopy (FTIR) and Transmission electron microscope (TEM) were used to analyze modification results. Composite resin specimen with modified SWCNTs were prepared and examined by TEM.â—†Results: TEM showed nano SiO₂ particles were on the surface of SWCNTs; FTIR showed absorbing bands of SiO₂ and siloxane network; and SWCNTs were detected dispersed well in composite resin.â—†Conclusions: Shell structure was formed on the surface of SWCNTs, and improved dispersion in dental composite resin was achieved.â—†Part 2 Influence of nano filler to the mechanical property of dental resin based composites (RBCs)â—†Experiment 1 Nano TiO₂ particles reinforced dental resin based compositesâ—†Objective: To study the effect of nano TiO₂ particles on the mechanical properties of dental resin based composites (RBCs).â—†Methods: Nano composites were prepared and their reinforced materials were modified and unmodified nano TiO₂ particles at a weight ratio of 0.5% and 1.0% respectively. Specimens with resin only were also set as control. Resin material was Z100^TM. Microhardness and flexural strength of composites were tested according to the standard. Statistical difference was analyzed by SPSS.â—†Results: Nano fillers can improve microhardness (P＜0.05), modified better than unmodified, 1.0%wt better than 0.5%wt. For flexural strength, modified ones can improved it, while unmodified can decrease it. And the performance of 1.0%wt was significant than that of 0.5%wt. â—†Conclusion: Microhardness and flexural strength of composites were influenced significantly by nano TiO₂ particles. Adding amount and surface modification were two important factors.â—†Experiment 2 Single walled Carbon nanotubes (SWCNTs) reinforced dental resin based composites (RBCs)â—†Objective: To study the effect of modified single walled carbon nanotubes (SWCNTs) on the mechanical properties of dental resin based composites (RBCs).â—†Methods: SWCNTs reinforced composites were prepared at a weight ratio of 0.1%. Specimens with resin only were set as control. Resin material was Durafill^? VS. The properties of composites were tested according to the standard. Statistical difference was analyzed by STATA (unequal Welch).â—†Results: Flexural strength of composites was increased significantly by modified SWCNTs.(P＜0.05)â—†Conclusion: The addition of modified SWCNTs can increase flexural strength of dental RBCs.