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

Effect of Rapid High-Intensity Light-Curing on Increasing Transdentinal Temperature and Cell Viability: An In Vitro Study

BACKGROUND

This study investigated effects of rapid high-intensity light-curing (3 s) on increasing transdentinal temperature and cell viability.

METHODS

A total of 40 dentin discs (0.5 mm) obtained from human molars were prepared, included in artificial pulp chambers (4.5 × 5 mm), and subjected to four light-curing protocols (n = 5), with a Valo Grand light curing unit: (i) 10 s protocol with a moderate intensity of 1000 mW/cm2 (Valo-10 s); (ii) 3 s protocol with a high intensity of 3200 mW/cm2 (Valo-3 s); (iii) adhesive system + Filtek Bulk-Fill Flow bulk-fill composite resin in 10 s (FBF-10 s); (iv) adhesive system + Tetric PowerFlow bulk-fill composite resin in 3 s (TPF-3 s). Transdentinal temperature changes were recorded with a type K thermocouple. Cell viability was assessed using the MTT assay. Data were analyzed using one-way ANOVA and Tukey tests for comparison between experimental groups (p < 0.05).

RESULTS

The 3 s high-intensity light-curing protocol generated a higher temperature than the 10 s moderate-intensity standard (p < 0.001). The Valo-10 s and Valo-3 s groups demonstrated greater cell viability than the FBF-10s and TPF-3 s groups and statistical differences were observed between the Valo-3 s and FBF-10 s groups (p = 0.023) and Valo-3 s and TPF-3 s (p = 0.025), with a potential cytotoxic effect for the FBF-10 s and TPF-3 s groups.

CONCLUSIONS

The 3 s rapid high-intensity light-curing protocol of bulk-fill composite resins caused a temperature increase greater than 10 s and showed cell viability similar to and comparable to the standard protocol.

Evaluation of dental pulp stem cells response to flowable nano-hybrid dental composites: A comparative analysis

BACKGROUND

Flowable resin composites (FRC) are tooth-colored restorative materials that contain a lower filler particle content, and lower viscosity than their bulk counterparts, making them useful for specific clinical applications. Yet, their chemical makeup may impact the cellular population of the tooth pulp. This in-vitro study assessed the cytocompatibility and odontogenic differentiation capacity of dental pulp stem cells (DPSCs) in response to two recent FRC material extracts.

METHODS

Extracts of the FRC Aura easyflow (AEF) and Polofil NHT Flow (PNF) were applied to DPSCs isolated from extracted human teeth. Cell viability of DPSCs was assessed using MTT assay on days 1, 3 and 7. Cell migration was assessed using the wound healing assay. DPSCs' capacity for osteo/odontogenic differentiation was assessed by measuring the degree of mineralization by Alizarin Red S staining, alkaline phosphatase enzyme (ALP) activity, and monitoring the expression of osteoprotegerin (OPG), RUNX Family Transcription Factor 2 (RUNX2), and the odontogenic marker dentin sialophosphoprotein (DSPP) by RT-PCR. Monomer release from the FRC was also assessed by High-performance liquid chromatography analysis (HPLC).

RESULTS

DPSCs exposed to PNF extracts showed significantly higher cell viability, faster wound closure, and superior odontogenic differentiation. This was apparent through Alizarin Red staining of calcified nodules, elevated alkaline phosphatase activity, and increased expression of osteo/odontogenic markers. Moreover, HPLC analysis revealed a higher release of TEDGMA, UDMA, and BISGMA from AEF.

CONCLUSIONS

PNF showed better cytocompatibility and enhancement of odontogenic differentiation than AEF.

Assessing the impact of dental restorative materials on fibroblast cells: an immunohistochemical and ELISA analysis

In this study, our aim was to investigate the effects of restorative materials such as composite, compomer and high viscosity glass ionomer, which are frequently used in dentistry, on L929 fibroblast cells by evaluating the oxidative stress parameters, pro- and anti-inflammatory cytokines, and apoptosis markers. L929 fibroblast cells were cultured, and dental filling materials were applied in two doses (50 and 100 µl). Immunohistochemical staining was performed for experimental groups with Anti-Bax and Anti-Caspase 9 antibodies. Then, ELISA technique was used to detect the level of TNF-alpha, TGF-beta, IL-1-beta, IL-6, IL-10, LPO and CAT. In the light of the data, the examined dental filling materials were effective on increasing the TGF-beta, IL-10, LPO and CAT levels, and decreasing the TNF-alpha, IL-1-beta, and IL-6 levels. The histological micrographs were also support the issues. When the levels of H-score in Caspase 9 labeled micrographs were evaluated, the mean of the control group was lower than the mean of the experimental groups. Biocompatibility varies according to the content of the material, the amount of residual monomer, and its solubility. Although all the experimental groups have cytotoxic effects, the least effect is seen in the Omnichroma group.

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.

Comprehensive proteomic and phosphoproteomic reveal that Microcystin-LR contributed to the malignant progression of gastric cancer by estrogenic potency

The widespread cyanotoxins in drinking water pose a threat to public health induced by Microcystins (MCs). MC-LR, a predominant toxic form of MCs, has been found to play critical roles in cancer progression. The role of MC-LR in hepatocarcinogenesis has attracted extensive attention. However, as a critical digestive organ, the precise mechanism of MC-LR-induced gastric cancer is still unclear. We found that 100 nM MC-LR promoted the proliferation, migration, invasion, and anti-apoptosis of SGC-7901 cells. Quantitative proteome and phosphoproteome analysis identified differential expression patterns and aberrant pathways of SGC-7901 cells exposed to MC-LR. The results indicated that 48,109 unique peptides from 6320 proteins and 1375 phosphoproteins with 3473 phosphorylation sites were detected after 24 h treatment of MC-LR. Proteome and phosphoproteome conjoint analysis indicated estrogen signaling pathway might play an essential step in MC-LR-treated molecular events. The mechanism underlying these changes may involve MC-LR excessively activating the estrogen signaling pathway by reducing Hsp90 phosphorylation, which results in nucleus translocation of activated ERα and Krt16 overexpression in gastric cells. In general, our results indicate multiple crucial signals triggered by MC-LR, among which MC-LR may promote the development of gastric cancer by exerting estrogenic potency.

Fe3O4 Nanoparticles in Combination with 5-FU Exert Antitumor Effects Superior to Those of the Active Drug in a Colon Cancer Cell Model

(1) Background: Colon cancer is one of the most common cancer types, and treatment options, unfortunately, do not continually improve the survival rate of patients. With the unprecedented development of nanotechnologies, nanomedicine has become a significant direction in cancer research. Indeed, chemotherapeutics with nanoparticles (NPs) in cancer treatment is an outstanding new treatment principle. (2) Methods: Fe3O4 NPs were synthesized and characterized. Caco-2 colon cancer cells were treated during two different periods (24 and 72 h) with Fe3O4 NPs (6 μg/mL), various concentrations of 5-FU (4−16 μg/mL), and Fe3O4 NPs in combination with 5-FU (4−16 μg/mL) (Fe3O4 NPs + 5-FU). (3) Results: The MTT assay showed that treating the cells with Fe3O4 NPs + 5-FU at 16 µg/mL for 24 or 72 h decreased cell viability and increased their LDH release (p < 0.05 and p < 0.01, respectively). Furthermore, at the same treatment concentrations, total antioxidant capacity (TAC) was decreased (p < 0.05 and p < 0.01, respectively), and total oxidant status (TOS) increased (p < 0.05 and p < 0.01, respectively). Moreover, after treatment with Fe3O4-NPs + 5-FU, the IL-10 gene was downregulated and PTEN gene expression was upregulated (p < 0.05 and p < 0.01, respectively) compared with those of the control. (4) Conclusions: Fe3O4 NPs exert a synergistic cytotoxic effect with 5-FU on Caco-2 cells at concentrations below the active drug threshold levels.

Mechanical Properties, Cytotoxicity, and Fluoride Ion Release Capacity of Bioactive Glass-Modified Methacrylate Resin Used in Three-Dimensional Printing Technology

Background: Clinically, three-dimensional (3D) printing technology is becoming a popular and efficient dental processing technology. Recently, there has been an increasing demand for dental materials that exhibit bioactive properties. The present study aimed to evaluate the mechanical properties, cytotoxicity, and fluoride ion release capacity of 3D-printed dental resins modified with bioactive glass. Materials and methods: The resin FotoDent splint used in the production of removable orthodontic splints, was modified by the addition of two types of bioactive glasses that are capable of releasing fluoride ions. The novel materials used for the production of dental splints were examined for their mechanical, physical, and biological properties (fracture resistance, sorption, solubility, elution of nonpolymeric substances, and release of fluoride ions over time) and cytotoxic effects on cell cultures. Results: Initially, the fracture toughness of the 3D-printed resin was found to be 55 MPa, but after modification with glass, the resistance was reduced to about 50 MPa. Sorption and solubility values of the materials (19.01 ÷ 21.23 µg/mm³ and 0.42 ÷ 1.12 µg/mm³, respectively) complied with the safety limits imposed by ISO standard. Modified resins were capable of releasing fluoride ions, and the maximum releasing effect was observed after 14 days of incubation. Both the modified resins, after four days of contact with human gingival fibroblasts, exhibited moderate cytotoxic properties. Conclusions: The experimental results showed that modification of methacrylate resin, used in 3D printing technology, with bioactive glasses produces novel dental materials that possess desirable bioactive properties. The findings of this study indicate the potential ability of modified polymethacrylate resins to release fluoride ions in the oral cavity environment. The modified materials are characterized with a moderate decrease in physical properties and mild cytotoxicity on direct contact with human fibroblasts.

Recent update on potential cytotoxicity, biocompatibility and preventive measures of biomaterials used in dentistry

Dental treatment is provided for a wide variety of oral health problems like dental caries, periodontal diseases, periapical infections, replacement of missing teeth and orthodontic problems. Various biomaterials, like composite resins, amalgam, glass ionomer cement, acrylic resins, metal alloys, impression materials, bone grafts, membranes, local anaesthetics, etc., are used for dental applications. The physical and chemical characteristics of these materials influence the outcome of dental treatment. It also impacts on the biological, allergic and toxic potential of biomaterials. With innovations in science and their positive results, there is also a need for awareness about the biological risks of these biomaterials. The aim of dental treatment is to have effective, yet safe, and long-lasting results for the benefit of patients. For this, it is important to have a thorough understanding of biomaterials and their effects on local and systemic health. Materials used in dentistry undergo a series of analyses before their oral applications. To the best of our knowledge, this is the first and original review that discusses the reasons for and studies on the toxicity of commonly used biomaterials for applications in dentistry. It will help clinicians to formulate a methodical approach for the selection of dental biomaterials, thus providing an awareness for forecasting their risk of toxic reactions.

Molecular Interactions between Saliva and Dental Composites Resins: A Way Forward

Dentin and enamel loss related to trauma or especially caries is one of the most common pathological issues in dentistry that requires restoration of the teeth by using materials with appropriate properties. The composite resins represent dental materials with significant importance in today’s dentistry, presenting important qualities, including their mechanical behavior and excellent aesthetics. This paper focuses on the saliva interactions with these materials and on their biocompatibility, which is continuously improved in the new generations of resin-based composites. Starting from the elements involved on the molecular landscape of the dental caries process, the paper presents certain strategies for obtaining more advanced new dental composite resins, as follows: suppression of oral biofilm acids formation, promotion of remineralization process, counteraction of the proteolytic attack, and avoidance of cytotoxic effects; the relation between dental composite resins and salivary oxidative stress biomarkers is also presented in this context.

Influence of resveratrol application with pulp-capping materials on the genetic expression levels of stem cells

AIM

To evaluate in a laboratory setting the response of human mesenchymal stem cells (MSCs) to pulp-capping materials with and without resveratrol (RSV).

METHODOLOGY

Five materials, Calcimol LC, Life, TheraCal LC, ProRoot MTA and Biodentine, were prepared according to the manufacturers' instructions. Human MSCs were then exposed to these materials, with and without RSV, for 24 h (n = 8). Cell viability was evaluated using the MTT assay, and total cell death was quantified by annexin V-FITC staining with flow cytometry. The expression levels of the IL-8, IL-10, HBD-2 and BCL-2 genes were investigated using real-time polymerase chain reaction (RT-PCR). Data obtained from MTT test were analysed using one-way anova, and Tukey's multiple-comparison test. The paired Student t test was employed to compare the effects of materials on gene expression (significance level of 5%).

RESULTS

The group cell viabilities were Calcimol LC 53%, Life 43%, TheraCal LC 78%, ProRoot MTA 75% and Biodentine 78%. Calcimol LC and Life exhibited significant differences compared with the control groups (P < 0.05). The percentages of necrotic/late apoptotic cells associated with Calcimol LC and TheraCal LC were greater than in the other materials. However, when RSV was added to wells containing materials, cell viability increased to Calcimol LC 63%, Life 52%, TheraCal LC 82%, ProRoot MTA 91% and Biodentine 96%, and the percentages of early apoptotic and late apoptotic/necrotic cells decreased. Calcimol LC + RSV and Life + RSV differed significantly from the control group (P < 0.05). The expression of IL-8 gene was high for all materials, ProRoot MTA caused significant overexpression, and the addition of RSV reduced the expression of IL-8 in the Calcimol LC, TheraCal LC and ProRoot MTA groups and led to increased expression of IL-10 in the Calcimol LC, Life and Biodentine groups. HBD-2 and BCL-2 exhibited increased expression in ProRoot MTA with RSV (P < 0.05).

CONCLUSIONS

The addition of RSV exerted a protective effect on MSCs and regulated the inflammatory process by altering the expression levels of pro- and anti-inflammatory genes.

Cadmium sulfide-induced toxicity in the cortex and cerebellum: In vitro and in vivo studies

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CdS NPs were synthesized using living organisms Viridibacillus arenosi K64.

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Morphology and size of NP were evaluated by XRD and SEM.

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In vitro studies revealed that CdS toxicity in cerebellum neuron is concentration dependent.

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In vivo study showed that CdS easily crosses blood brain barrier.

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CdS in high doses induces toxicity in both neuron and purkinje cells in rats.

Living organisms have an innate ability to regulate the synthesis of inorganic materials, such as bones and teeth in humans. Cadmium sulfide (CdS) can be utilized as a quantum dot that functions as a unique light-emitting semiconductor nanocrystal. The increased use in CdS has led to an increased inhalation and ingestion rate of CdS by humans which requires a broader appreciation for the acute and chronic toxicity of CdS. We investigated the toxic effects of CdS on cerebellar cell cultures and rat brain. We employed a ‘green synthesis’ biosynthesis process to obtain biocompatible material that can be used in living organisms, such as Viridibacillus arenosi K64. Nanocrystal formation was initiated by adding CdCl₂ (1 mM) to the cell cultures. Our in vitro results established that increased concentrations of CdS (0.1 μg/mL) lead to decreased cell viability as assessed using 3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide (MTT), total antioxidant capacity (TAC), and total oxidant status (TOS). The in vivo studies showed that exposure to CdS (1 mg/kg) glial fibrillary acidic protein (GFAP) and 8-hydroxy-2' -deoxyguanosine (8-OHdG) were increased. Collectively, we describe a model system that addresses the process from the synthesis to the neurotoxicity assessment for CdS both in vitro and in vivo. These data will be beneficial in establishing a more comprehensive pathway for the understanding of quantum dot-induced neurotoxicity.

Effect of preheating on the cytotoxicity of bulk-fill composite resins

Background. Due to the effect of pre-heating on the degree of conversion of composite resins and the possible effect on cytotoxicity, the effect of pre-heating of bulk-fill composite resins was investigated on cytotoxicity in this study. Methods. In this study, three different types of composite resin were used, including Tetric N-Ceram Bulk-Fil, Xtrafil, and Xtrabase. From each composite resin, 10 cylindrical samples (5 mm in diameter and 4 mm in height) were prepared, with five samples preheated to 68°C, and the other five samples polymerized at room temperature (25°C). Twenty-four hours after polymerization, cytotoxicity was assessed by MTT assay on human fibroblasts. Statistical analysis of data was carried out with two-way ANOVA and Sidak Post-Hoc. The significance level of the test was determined at 0.05. Results. There was no statistically significant difference between the mean percentage of cytotoxicity in terms of pre-heating (P>0.05), but the cytotoxicity of the studied composite resins was significantly different (P<0.001). The cytotoxicity of Tetric N-Ceram Bulk-fil composite resin was higher than that of the two other composite resins. Conclusion. Pre-heating of bulk-fill composite resin did not affect their cytotoxicity. In addition, the cytotoxicity of different bulk-fill composite resins was not the same.

Depth-Dependent Cellular Response from Dental Bulk-Fill Resins in Human Dental Pulp Stem Cells

The proper choice of dental composite resins is necessary based on the minimal cytotoxicity and antiodontogenesis on human dental pulp stem cells for dental pulp-dentin tissue repair and regeneration. The aim of this study was to evaluate the cytotoxicity and antidifferentiation effects of dental bulk-fill resins, able to be polymerized as a bulk status for filling deep cavity of a tooth by single light curing, against human dental pulp stem cells (hDPSCs) from three compartments corresponding to depth (0-2, 2-4, and 4-6 mm) from the light-curing site. Three bulk-fill composite resins (SDR, Venus bulk-fill (VBF), and Beautifil Bulk Flowable (BBF)) and a conventional flowable composite resin (Filtek Z350 XT flowable restorative (ZFF)) were individually filled into a cylindrical hole (h = 2 mm, Ф = 10 mm), and three compartments (total ~6 mm of height) were combined as a single assembly for light curing. The resin samples from the three layers were separated and eluted in the culture medium. The extracts were exposed to hDPSCs, and cytotoxicity and differentiation capability were evaluated. Depth of cure and surface hardness according to depth were determined. All bulk-fill resins except BBF revealed cytotoxicity from 4 to 6 or 2 to 4 mm, while ZFF was cytotoxic at over 2 mm. Depth of cure was detected from 3.55 to 4.02 mm in the bulk-fill resins (vs. ~2.25 mm in conventional resin), and 80% hardness compared with that of a fully polymerized top surface was determined from 4.2 to 6 mm in the bulk-fill resin (vs. 2.4 mm in conventional resin). Antidifferentiation was revealed at a depth of 4-6 mm in the bulk-fill resin. There was a difference in depth of cytotoxicity and antidifferentiation between the bulk-fill composite resins, which was mainly due to different cure depths and ingredients. Therefore, careful consideration of choice of bulk-fill resins is necessary especially for restoration of deep cavities for maintaining the viability and differentiation ability of dental pulp stem cells.