Genotoxic potential of dental bulk-fill resin composites

Abstract

Bulk-fill resin composites, in contrast to conventional composite, applied in 4-mm thickness and photo-activated for at least 20s do not induce relevant genotoxic effects or mechanical instability.

Physicomechanical characterization and biological evaluation of bulk-fill composite resin

“…31 Among flowable resins, XTB presented better VH than the other materials, which suggests that the data obtained are related to the load content of each material (manufacturer's information), thus corroborating the findings of Zorzin et al 32 and of Ashali et al 33 The data obtained in this work did not reveal a significant reduction in microhardness on the polymerization surface, indicating adequate monomer conversion. Similar results were reported by Tauböck et al 5 As regards the degree of conversion, no influence of the thickness and surface subjected to polymerization was observed. Degree of conversion at the top and bottom of all resin specimens was greater than the clinically recommended values (> 55%), according to Alshali et al, 34 except for AFB (4 mm) Z350F, Opus, and FBFF (2 mm) at the bottom.…”

“…This allows greater penetrability of the photopolymerizing light, thereby increasing the depth of cure. 5 However, ABF presented low degree of conversion on the bottom surface at 4 mm (20%), without statistical significance, drawing attention to the influence of the material on the varied results obtained. 35 Statistical differences were observed among the evaluated materials, as expected, since degree of conversion is influenced by variables such as composite type, monomer composition, inorganic fraction, mass viscosity, reaction temperature, thickness of the increment, among others.…”

“…21 The exact mechanism by which this occurs has not yet been established in the literature; however, the reduction in cellular glutathione levels 22 and the increase in the levels of reactive oxygen species (ROS) are believed to be the main triggers; 23 in addition, the latter has been associated with damage to cellular DNA exposed to methacrylate. 24 On the other hand, Tauböck et al 5 reported that the tested bulk-fill resins did not induce significant genotoxic effects on cellular DNA. The second hypothesis, which posited that there would be no difference between the methods used for evaluating cytotoxicity, was also rejected.…”

“…2 Although composite resins are biologically accepted, there has been evidence of allergic effects on oral mucosal tissues, 3 due to the dissolution of methacrylate and leaching of its components, 4 resulting from masticatory forces and chemical degradation. 5 Thus, composite resins, known as bulk-fill resins, with modifications in their chemical formulation and polymerization properties, have been developed to minimize or eliminate polymerization shrinkage, increasing the depth of polymerization as well as cytotoxicity. Bulk-fill resins with a 4-6 mm single increment have low shrinkage stress and a high degree of polymerization at this depth, due in particular to the increase in translucency and to the presence of polymerization modulators.…”

Polymerization shrinkage and shrinkage force kinetics of high- and low-viscosity dimethacrylate- and ormocer-based bulk-fill resin composites

“…In an attempt to simplify and expedite the placement of direct composite restorations, so-called bulk-fill resin composites have been introduced to the dental profession. These materials are characterized by an increased depth of cure compared with conventional resin composites, allowing thick layers of up to 4-5 mm to be placed and photo-polymerized in a single step [1][2][3][4]. Besides saving clinical time, bulk placement can prevent incorporation of voids or contaminants between composite layers [5][6][7].…”