Mechanical properties of dental composite resins containing nanodiamond of different diameters

In order to investigate the effect of nanodiamond (ND) on the mechanical properties of dental composite resins, bisphenol-A-glycidyl dimethacrylate (Bis-GMA), triethylene glycol dimethacrylate (TEGDMA), barium glass (BG) powder, DL-camphoroquinone (CQ) and dimethylaminoethylmethacrylate (DMAEMA) were mixed as the matrix for the experiments. NDs of three diameters (100 nm, 220 nm, 500 nm) modified with 3-(trimethoxysilyl) propyl methacrylate (γ-MPS) were added to the mixture separately in 0.2% to get test samples. The flexural strength and elastic modulus of these samples and the mixture without ND (as the reference group, RG) were characterized with standard specification tests. Results reveal that the mechanical properties and elastic modulus of resins containing 220 nm ND (R-220) and 500 nm ND (R-500) were significantly different from those of RG. R-500 had the highest flexural strength and elastic modulus (by average data), and all of its five specimens were found to have mean flexural strength values greater than the minimum value (80MPa) prescribed by ISO 4049:2000. Different sizes of diamonds have different effects on mechanical properties of dental composite resins, and the performances of 220 nm and 500 nm diamonds are better than that of 100 nm diamond.