Contrast-to-noise ratios of different dental restorative materials: an in-vitro cone beam computed tomography study.

PURPOSE: In radiological views, strong beam hardening and streaking artifacts occur due to high-density structures and polyenergetic X-ray beams, and these lead to misdiagnosis. This study was performed in vitro to compare the contrast-to-noise ratio (CNR) of commonly used dental restorative materials by using Cone Beam Computed Tomography (CBCT) images with and without artifact reduction (AR) mode. MATERIALS AND METHODS: A total of 108 molar teeth were restored with nine different groups of restorative materials, with each group containing 12 teeth. Teeth were placed in a dry human mandible and scanned, one by one, via Planmeca 3D ProMax (Planmeca, Helsinki, Finland) with and without AR mode. Images were analyzed using ImageJ software (National Institutes of Health, Bethesda, MD) to calculate the CNR. RESULTS: CNR was calculated to be the highest in compomer (Glassiosite) images without AR mode (mean: 3.36) and with AR mode (mean: 3.61). CNR was calculated to be the lowest in amalgam (Tytin) images without AR mode (mean: 0.21) and with AR mode (mean: 0.23). A significant difference was found between materials in terms of CNR measurements (p ≤ 0.05). CNR measurements were increased after the AR mode application (p ≤ 0.05). CONCLUSION: AR mode was effective in reducing artifacts arising from dental materials on CBCT images, so it is necessary to use AR mode for correct diagnoses.

Cytotoxic effects of new-generation bulk-fill composites on human dental pulp stem cells.

This study was performed to evaluate possible DNA damage in cells of human origin exposed to dental composites in vitro using a cytotoxic assay. Five bulk-fill composites were filled in molds and irradiated for 20 s. DPSCs were inoculated into 24-well plates. After the insert membrane was inserted and composites were added and the experiment was continued for 24/72 hours. In order to investigate the effects of the materials on DPSCs; its effect on apoptosis-regulating Bcl-2 gene, Human Beta-Defensins (HBDs 1-2) gene, Interleukin 6, 8, 10 expression level was examined. Also in order to check the cellular viability and stress factors; MTT assay, Total Antioxidant and Oxidant Status kits were used. At both irradiation times, all composites significantly affected analyses parameters used in primary DNA damage assessment or induced significant formation of cellular death. Cytotoxicity was detected in TE<SS<FBF<XB<VBF groups at 24 hour, and after 72 hour this sequence has changed.

Cytotoxic and biological effects of bulk fill composites on rat cortical neuron cells.

The aim of this study was to investigate potential cellular responses and biological effects of new generation dental composites on cortical neuron cells in two different exposure times. The study group included five different bulk-fill flow able composites; Surefil SDR Flow, X-tra Base Flow, Venus Bulk Flow, Filtek Bulk Flow and Tetric-Evo Flow. They were filled in Teflon molds (Height: 4 mm, Width: 6 mm) and irradiated for 20 s. Cortical neuron cells were inoculated into 24-well plates. After 80% of the wells were coated, the 3 µm membrane was inserted and dental filling materials were added. The experiment was continued for 24 and 72 h. Cell viability measured by MTT assay test, total antioxidant and total oxidant status were examined using real assay diagnostic kits. The patterns of cell death (apoptosis) were analyzed using annexin V-FITC staining with flow cytometry. Β-defensins were quantitatively assessed by RT-PCR. IL-6, IL-8 and IL-10 cytokines were measured from the supernatants. All composites significantly affected analyses parameters during the exposure durations. Our data provide evidence that all dental materials tested are cytotoxic in acute phase and these effects are induced cellular death after different exposure periods. Significant cytotoxicity was detected in TE, XB, SS, FBF and VBF groups at 24 and 72 h, respectively.