Wear of nanofilled dental composites at varying filler concentrations

Abstract

The aim of this study is to examine the effects of nanofiller concentration on the mechanisms of wear of a dental composite. Nanofilled composites were fabricated with a bisphenol A glycidyl methacrylate polymer and 40 nm SiO2 filler particles at three filler loads (25, 50, and 65 wt %). The elastic modulus, flexural strength, and hardness of the composites and the unfilled resin were measured. The materials (n = 8) were tested in the modified wear testing device at 50,000, 100,000, and 200,000 cycles with 20N force at 1 Hz. A 33% glycerine lubricant and stainless steel antagonist were used. The worn composite and antagonist surfaces were analyzed with noncontact profilometry and SEM. The volumetric wear data indicated that there are significant differences between filler concentrations and cycles (p < 0.05). A trend was noted that increasing filler content beyond 25% decreased the wear resistance of the composites. Increasing filler content increased hardness and modulus and increased flexural strength up to 50% fill. SEM evaluation of the worn specimens indicated that the resin and 25% filled materials exhibited cracking and failed by fatigue and the 50 and 65% filled materials exhibited microcutting and failed by abrasive wear. Based on the results of this study, composite manufacturers are recommended to use a filler concentration between 25 and 50% when using nanosized filler particles.

Development and status of resin composite as dental restorative materials

“…The source of the acid may come from food and oral microorganism(Figure ). Wear resistance of dental composites was one of the major clinical concerns for posterior restorations about a decade ago, while the current composites are fine …”

“…The wear resistance of composites is mainly determined by the resin formulation and filler particle distribution . Different shapes and combinations of size of filler particles are associated with the wear performance of composites.…”

“…found the mechanical properties and abrasion resistance of the nanofiller resin composites were improved compared with traditional filler resin composites. Lawson and Burgess suggested that the content of the nanofiller should be controlled between 25 and 50% to achieve better mechanical properties of the material, while higher than 50% of the filler will coagulate and lead to fracture defects. The degree of cure of the polymer matrix also has been shown to have significant effect on intraoral wear resistance of composites.…”

“…Wear resistance of dental composites was one of the major clinical concerns for posterior restorations about a decade ago, while the current composites are fine. 61,62 The wear resistance of composites is mainly determined by the resin formulation and filler particle distribution. 61 Different shapes and combinations of size of filler particles are associated with the wear performance of composites.…”

In vitro evaluation of adhesive characteristics of 4-META/MMA-TBB resin with organic filler

“…Theoretically, filler content of a resin composite material is related to various properties of the material. Thus modifying resin composition by adding fillers could affect properties such as compressive strength, wettability [17], wear resistance [18] and polymerization shrinkage [19]. Adding 2% of untreated poly methyl methacrylate (PMMA) fillers to MMA improved physical properties, but more (23.1%) caused debonding between matrix and fillers [17].…”