Evaluation of cytotoxicity and microhardness of three different posterior composite materials

The aim of this study; evaluation of the polymerization depths by microhardness test and the biocompatibility by in-vitro cytotoxicity test of a conventional posterior composite resin and two different bulk-fill posterior composite resin. FiltekTM Z550 Kompozit Rezin, Tetric N-Ceram Bulk Fill Kompozit Rezin and FiltekTM Bulk Fill Posterior Kompozit Rezin were used as a restorative material. In the first part of the study, microhardness of composite resins were evaluated and in the second part, in-vitro cytotoxicity of composite resins were evaluated. For the microhardness test; 10 specimens of each composite resin were obtained using teflon molds of 2, 4, 5 mm in thickness and 5 mm in diameter. A total of 30 specimens were polymerized using a LED light curing unit. After polymerization, specimens were incubated in the dark at 37°C for 24 h. Microhardness evaluation was performed at top and bottom surfaces for each specimen using a Vickerʼ s microhardness tester. Each sample was recorded by calculating the hardness ratio. Data were analyzed by using one way analysis of variance (Oneway ANOVA) and Tukey HSD test. For the cytotoxicity test; 12 specimens of each composite resin were obtained using teflon molds with thicknesses of 2, 4, 5 mm and a diameter of 5 mm. A total of 36 specimens were polymerized using a LED light curing unit. The samples were incubated in RPMI 1640 medium at 37°C for 24, 48 and 72 h and extraction liquids were obtained. After the incubation periods, cell viability was assessed by MTT assay. MTT assay was repeated in three seperate experiments. Data were analyzed by using Kruskal Wallis analysis of variance and Mann Whitney U test. According to the results obtained from the microhardness test; the top and bottom surface microhardness values of composite resins were listed as Filtek ™ Z550 Composite Resin> Filtek ™ Bulk Fill Posterior Composite Resin> Tetric N-Ceram Bulk Fill Composite Resin. Obtained microhardness values were found statistically significant. Filtek ™ Z550 Composite Resin microhardness ratio was significantly higher than the other composite resins when the bottom surface/top surface microhardness ratios were compared. The difference between the bottom surface/top surface microhardness ratios of the Filtek™ Bulk Fill Posterior Composite Resin and the Tetric N-Ceram Bulk Fill Composite Resin was not statistically significant. However, all composite resins provide ideal polymerisation depth. According to the results obtained from the cytotoxicity test; for the 24 and 48 h incubations, there were no statistically significant difference between the composite resins cytotoxicity. But, for the 72 h incubation, Filtek ™ Bulk Fill Posterior Composite Resin showed the highest cytototoxic effect amoung the other groups which was statistically significant. Furthermore, the cytotoxicity of Filtek ™ Bulk Fill Posterior Composite Resin for 72 h incubation was found higher than for 24 and 48 h incubations statistically significant. When the results of the study are evaluated, it is observed that bulk-fill composite resins provide ideal polymerisation depths like traditional composite resins. At the same time, the cytotoxicity values were not found to be significant in all study groups which the depth of polymerization was sufficient except for the 72 h incubation of the Filtek ™ Bulk Fill Posterior Composite Resin. As a result of the obtained results, we can say that it is necessary long-term and a lot of studies to suggest an ideal composite resin.