Comparison of cytotoxicity test models for evaluating resin-based composites

Abstract

<jats:sec><jats:title>Objectives:</jats:title><jats:p> This study compared different cytotoxicity test models for evaluating resin-based composites (RBCs) and assessed the biocompatibility of standard and bulk-fill RBCs. </jats:p></jats:sec><jats:sec><jats:title>Methods:</jats:title><jats:p> A standard (spectrum TPH) and a bulk-fill (smart dentin replacement (SDR)) RBC were selected. Disc-shaped specimens (7 mm diameter) of 2 and 4 mm thickness were polymerized for 20 s with a LED curing light of 700 mW/cm<jats:sup>2</jats:sup> irradiance. The specimens ( n = 5) were subjected to micro-hardness testing and three cytotoxicity test models (direct contact, indirect contact and extract tests) with the established L-929 cell line. Hardness ratios of top and bottom surfaces of specimens were computed to assess the effectiveness of cure. For the direct and indirect contact tests, the cells were stained and zones of inhibition were analyzed after material contact for 24 h. For the extract test, cells were exposed to extracts for 24 h, and cell viability was measured. Data was analyzed using analysis of variance/Scheffe’s post hoc test and Pearson’s correlation ( p &lt; 0.05). </jats:p></jats:sec><jats:sec><jats:title>Results:</jats:title><jats:p> The lowest mean hardness ratio and highest cytotoxicity were observed for TPH at 4 mm. At 4-mm thickness, SDR was found to be biocompatible with all three models. Correlations between hardness ratio and cell viability ranged from r = 0.89–0.96 for the various tests. A significant correlation ( r = 0.97) was also observed between the three test models. </jats:p></jats:sec><jats:sec><jats:title>Conclusion:</jats:title><jats:p> Our data indicated consistency between direct contact, indirect contact and extract test models for cytotoxicity testing of RBCs. Bulk placement and curing at 4 mm for the bulk-fill RBC evaluated did not result in undue cytotoxicity. </jats:p></jats:sec>

Cytotoxic effects of contemporary bulk-fill dental composites: A real-time cell analysis

“…Bulk-fill resin composites have gained popularity among clinicians, since they allow the placement of thicker layers and thus provide simplified and time-saving restorative procedures. While their physico-mechanical properties, curing characteristics and wear performance have been extensively investigated [16][17][18][19][20][21] , scientific data on the biocompatibility of bulk-fill composite materials are still limited [13][14][15] .…”

“…To date, several in vitro test designs have been recommended by the International Standards Organization (ISO) 10993 protocols for assessing the cytotoxicity of dental biomaterials (ISO 10993-5:2009, ISO 10993-12:2012) These include the direct contact test model where dental material and cell lines are placed in direct contact; the indirect contact test model, where a barrier is placed between the dental material and cell layer; and finally the extract test model, where the cells are exposed to the extract of the dental material 13,14) . In this study, tested composite resin discs were placed in plates wherein the cells were incubated so as to provide direct contact between the cells and composite samples.…”

“…Studies investigating the cytotoxicity of bulk-fill composites are still limited [13][14][15] and none have compared the cytotoxicity of the flowable and paste-like bulk-fill composite of the same brand. Moreover, to date there is no study investigating the cytotoxicity of bulk-fill composites using a real time cell analysis.…”

Evaluating Cytotoxic Effects of Highly Esthetic Dental Composites

“…These are direct contact (direct method), indirect contact with a barrier (indirect method) and (extract method) in which extracts from biomaterials are added onto cells. Lim et al [17] in their study comparing the in vitro test models used in the evaluation of the cytotoxicity of composite resins, suggested preferring the extract test method because of its higher sensitivity if a single test model is used.…”

Organic Eluates Derived from Intermediate Restorative Dental Materials

“…Manufacturers allege that these formulations might enhance the depth of cure by up to 4 mm [21,22]. However, there are concerns about the complete polymerization and the presence of unreacted monomers in the mass of these materials [23,24].…”