Influence of the degree of conversion and Bis-GMA residues of bulk fill resins on tissue toxicity in an subcutaneous model in rats

In Vitro Cytotoxic and Inflammatory Response of Gingival Fibroblasts and Oral Mucosal Keratinocytes to 3D Printed Oral Devices

The purpose of this study was to examine the biocompatibility of 3D printed materials used for additive manufacturing of rigid and flexible oral devices. Oral splints were produced and finished from six printable resins (pairs of rigid/flexible materials: KeySplint Hard [KR], KeySplint Soft [KF], V-Print Splint [VR], V-Print Splint Comfort [VF], NextDent Ortho Rigid [NR], NextDent Ortho Flex [NF]), and two types of PMMA blocks for subtractive manufacturing (Tizian Blank PMMA [TR], Tizian Flex Splint Comfort [TF]) as controls. The specimens were eluted in a cell culture medium for 7d. Human gingival fibroblasts (hGF-1) and human oral mucosal keratinocytes (hOK) were exposed to the eluates for 24 h. Cell viability, glutathione levels, apoptosis, necrosis, the cellular inflammatory response (IL-6 and PGE2 secretion), and cell morphology were assessed. All eluates led to a slight reduction of hGF-1 viability and intracellular glutathione levels. The strongest cytotoxic response of hGF-1 was observed with KF, NF, and NR eluates (p < 0.05 compared to unexposed cells). Viability, caspase-3/7 activity, necrosis levels, and IL-6/PGE2 secretion of hOK were barely affected by the materials. All materials showed an overall acceptable biocompatibility. hOK appeared to be more resilient to noxious agents than hGF-1 in vitro. There is insufficient evidence to generalize that flexible materials are more cytotoxic than rigid materials. From a biological point of view, 3D printing seems to be a viable alternative to milling for producing oral devices.

Properties of Nanohybrid Dental Composites-A Comparative In Vitro Study

(1) Background: the current study investigated three nanohybrid composites: two commercial products ClearfilMajestyTM (CM) and HarmonizeTM (HU), compared with an experimental product PS2. (2) Methods: Two sample types were molded using Teflon dies. The first sample type was represented by standard discs (20 mm diameter and 2 mm thickness) (n = 60, 20/each material), used for surface conditioning investigation, specifically roughness monitoring and color stability analysis using AFM and the CIELab test, respectively. The second sample type was a standard cylindrical specimen (4 mm diameter and 6 mm height) for compression testing (n = 60, 20/each material). After complete polymerization, the samples were ground with sandpaper and further polished. The filler size and distribution in the polymer matrix were investigated with SEM. Data were statistically analyzed using the Anova Test followed by Tukey's post hoc test on the Origin Lab 2019 software produced by OriginLab Corporation, Northampton, MA, USA. (3) Results: A mono-disperse system was identified in HU samples, while CM and PS2 revealed both nano- and microfiller particles. The samples' observation after immersion in coffee and tea indicated that a lower roughness combined with optimal filler lamination within the polymer matrix assured the best color preservation. The compression strength was lower for the HU sample, while higher values were obtained for the complex filler systems within CM and PS2. (4) Conclusions: the behavior of the investigated nanohybrid composites strongly depends on the microstructural features.

Biocompatibility of bulk-fill resins in vitro

OBJECTIVES

This study aims to evaluate the cytotoxicity and genotoxicity of three different extracts obtained from Filtek™ One Bulk Fill, Tetric Evoceram® Bulk Fill and Coltene Fill-Up! resins.

MATERIALS AND METHODS

The cytotoxicity was determined on 3T3 fibroblast cells using the MTT and crystal violet assays. The genotoxicity was determined using a cytokinesis-block micronucleus assay.

RESULTS

The cytotoxicity of the resin extracts on 3T3 mouse fibroblasts was found to be dose-dependent with both the MTT and crystal violet assays. Extracts concentrated above 1% were cytotoxic according to the MTT assay. The Filtek™ One Bulk Fill, Tetric Evoceram® Bulk Fill, and Coltene Fill-Up! resins reached the LD50 at concentrations of 60%, 50%, and 20%, respectively, and showed genotoxicity rates that were 2-5 times, 3-8 times, and 4-15 times higher than the negative control, respectively.

CONCLUSIONS

Coltene Fill-Up! resin extracts were the most cytotoxic and genotoxic, followed by Tetric Evoceram® Bulk Fill and Filtek™ One Bulk Fill.

CLINICAL RELEVANCE

The analyzed bulk-fill resins showed differences in in vitro biocompatibility, and the Filtek™ One Bulk Fill was found to be the safest for clinical use.

Rutin alleviates bisphenol A-glycidyl methacrylate-induced generation of proinflammatory mediators through the MAPK and NF-κB pathways in macrophages

Bisphenol A-glycidyl methacrylate (BisGMA) is a methacrylate monomer that is mainly used in three-dimensional structures to reconstruct dental and bony defects. BisGMA has toxic and proinflammatory effects on macrophages. Rutin is a natural flavonol glycoside that is present in various plants and has useful biological effects, such as anti-inflammatory, anticancer, and antioxidative effects. The aim of this study was to investigate the anti-inflammation of rutin in macrophages after exposure to BisGMA. Pretreatment of the RAW264.7 macrophage with rutin at 0, 10, 30, and 100 μM for 30 min before being incubated with BisGMA at 0 or 3 μM. Proinflammatory cytokines and prostaglandin (PG) E2 were detected by enzyme-linked immunosorbent assay (ELISA). Nitric oxide (NO) was detected by the Griess assay. Expression and phosphorylation of proteins were measured by Western blot assay. Pretreatment with rutin inhibited the BisGMA-induced generation of proinflammatory cytokines, including tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, and PGE2, in macrophages. Rutin also suppressed the BisGMA-induced secretion of NO and expression of inducible nitric oxide synthase (iNOS) in a concentration-dependent manner. Furthermore, rutin suppressed the mitogen-activated protein kinase (MAPK) phosphorylation in a concentration-dependent manner. Finally, rutin suppressed the BisGMA-induced phosphorylation of nuclear factor (NF)-κB p65 and degradation of inhibitor of κB (IκB). These results indicate that the concentration of rutin has an inhibitory effect on proinflammatory mediator generation, MAPK phosphorylation, NF-κB p65 phosphorylation, and IκB degradation. In conclusion, rutin is a potential anti-inflammatory agent for BisGMA-stimulated macrophages through NF-κB p65 phosphorylation and IκB degradation resulting from MAPK phosphorylation.

Protective effect of wogonin on inflammatory responses in BisGMA-treated macrophages through the inhibition of MAPK and NFκB pathways

Composites, resins, and sealants that are commonly used in orthopedics and dentistry are based on 2,2-bis[p-(2'-hydroxy-3'-methacryloxypropoxy)phenylene]propane (BisGMA), which induces proinflammatory responses in macrophages. The present study aimed to explore the anti-inflammatory responses of wogonin, which is a natural dihydroxyl flavonoid compound, in BisGMA-treated macrophages. According to the findings, wogonin exhibits anti-inflammatory, antiallergic, anticancer, and antioxidative properties. The generation of nitric oxide (NO) and the expression of inducible nitric oxide synthase (iNOS) were noted to be inhibited by wogonin in BisGMA-treated macrophages. Furthermore, the production of proinflammatory cytokines including tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 was reduced. In addition, BisGMA-induced nuclear factor (NF)-κB p65 phosphorylation and inhibitor of κB (IκB) degradation were inhibited. Finally, the BisGMA-induced phosphorylation of mitogen-activated protein kinases (MAPKs), including p38 MAPK, extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) was inhibited. All these effects were induced by wogonin in the macrophages in a concentration-dependent manner. Similar inhibitory effects of wogonin were observed on the production of NO and proinflammatory cytokines, expression of iNOS, phosphorylation of NF-κB p65 and MAPK, and degradation of IκB. These results indicated that rutin is a potential anti-inflammatory agent for BisGMA-treated macrophages that undergo NFκB p65 phosphorylation and IκB degradation through upstream MAPK phosphorylation. Therefore, wogonin inhibits BisGMA-induced proinflammatory responses in macrophages through the regulation of the NFκB pathway and its upstream factor, MAPK.