Physicomechanical characterization and biological evaluation of bulk-fill composite resin

Abstract

The aim of this study was to evaluate the cytotoxic effect, degree of conversion (% DC), Vickers hardness (VH), and surface morphology of composite resins. Eleven resins, nine bulk-fill resins, and two conventional resins were evaluated. Each material was sampled to evaluate DC (using FTIR), VH, cytotoxicity (using MTT and Neutral Red -NR test), surface morphology (using SEM and AFM), and organic filler (using EDS). All statistical tests were performed with SPSS and the level of significance was set at 0.05. MTT revealed that the materials presented low or no cytotoxic potential in relation to the control. Opus was the resin with the lowest cell viability at a 1:2 concentration at 72 h (32%) and at 7 days (43%), but that significantly increased when the NR test was applied at a 1:2 concentration after 7 days. Thickness and surface subjected to polymerization had no influence on DC, and differences were observed only between the materials. In the microhardness test, statistical differences were observed between the evaluated thicknesses. The bulk-fill resins analyzed in this study exhibited low and/or no cytotoxicity to L929 cells, except for Opus, which showed moderate cytotoxicity according to the MTT assay. When the NR test was used, results were not satisfactory for all composites, indicating the need for different methodologies to evaluate the properties of these materials. The assessed resins demonstrated acceptable physicomechanical properties.

Hybrid Dental Composites Biomechanical Properties

“…Although it's a microfilled hybrid composite, Gradia ® showed a approximately 50% lower HV value compared cu Ceramage ® ; our results disagree the ones obtained by Rastelli, Kyo-Han and Nascimento, which showed that microfilled composites have a higher hardness compared to nanofilled composited [14,22,23]. Premise TM composite have a similar filling with X-tra Fil (Voco GnbH, Germany) or Filtek (3M ESPE, Dental Production Division, MN, USA), but because of adding the precured filler, Premise's HV was 30% higher [23,24].…”

Biocompatibility Evaluation of Resin-Based Restorative Materials: A Review

“…Nascimento at al. 60 revealed different re-sults between the neutral red and MTT tests. Rajic et al 63 found that cured forms of composites did not show any toxic effect, whereas uncured forms exhibited a certain level of toxicity.…”

“…2,3 Many in vitro studies have been conducted to determine cytotoxicity of resin-based restorative materials and contradictory results have been obtained. 19,59,60 The results show differences depending on the resin composition of the material, cell type or test methods. Human cell lines are found to be more sensitive to long-term incubation with composites than mammalian cell lines.…”

Effect of thickness on shrinkage stress and bottom‐to‐top hardness ratio of conventional and bulk‐fill composites

“…Bulk-fill composites were launched in the market aiming to decrease clinical time and minimize dimensional shrinkage (11,(14)(15)(16)(17)(18). The compositional modifications allow these materials to be inserted in a single increment of up to 5 mm thickness, and may involve the addition of monomers with higher molecular weight, modulators of polymerization, increase of translucency, use of photo-initiators with higher reactivity, and larger filler particles (6,9,11,16,19).…”

“…For bulk-fill composites, the main advantage is a greater polymerization capacity, that is, an increase in the degree of conversion and curing depth, enabling its use in large increments (24,26). Considering the adverse biological effects of some monomers (15,27), the manufacturers of APS composites highlight the absence of Bisphenol-A Glycidyl Methacrylate (Bis-GMA), a highly viscous high molecular weight monomer, in these composites. In the absence of Bis-GMA, only small amounts of diluent monomers might be present in these materials, which would contribute to the reduction of shrinkage stress (3,7).…”