Comparative evaluation of dental resin composites based on micron- and submicron-sized monomodal glass filler particles

Objectives. A model resin composite containing a novel monomodal inorganic filler system based on submicron-sized Ba-Si-Al glass particles (NanoFine NF180; Schott) was formulated and compared with an experimental composite containing micron-sized particles (UltraFine UF1.0; Schott). Methods. The filler particles were characterized using X-ray microanalysis and granulometry, while the composites were characterized in terms of filler-resin morphology, radiopacity, degree of C=C conversion, hardness, flexural strength/modulus, work-of-fracture, surface roughness and gloss (before and after simulated toothbrushing abrasion), and bulk compressive creep. The composites were formulated from the same photoactivated dimethacrylate co-monomer, incorporating mass fractions of 75% micron- and 78% submicron-sized particles. Quantitative data were analyzed at a significance level of p <0.05. Results. Both filler systems exhibited a narrow grain size range (175 +/- 30 and 1000 200 nm), with differences restricted to the size and specific area of the particles. The composites were similar in radiopacity, flexural strength, work-of-fracture, and creep. The submicron composite was harder but had lower flexural modulus and C=C conversion. No significant differences in roughness were observed before brushing, although the submicron composite had higher gloss. Brushing increased roughness and decreased gloss on both materials, but the submicron composite retained higher gloss after brushing. Signcance. The monomodal submicron glass filler system demonstrated potential for use in restorative dental composites, particularly due to improved esthetic properties. (C) 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.