Evaluation of the cytotoxicity of different root canal sealers on L929 cell line by MTT assay

Biofunctionalized Nanomaterials: Alternative for Encapsulation Process Enhancement

In recent years, interest in the development of nanometric materials with specific characteristics has grown; however, there are few scientific contributions that associate encapsulation methodologies and matrices with the particle objective (metabolic directions, type of administration, biological impact, and biocompatibility). This review focuses on describing the benefits and disadvantages of different techniques for designing custom particles and alternatives for the biofunctionalization nanomaterials regarding the biological impact of a nanomaterial with potential use in foods known as nutraceuticals. The study of optical properties, physicochemical factors, and characteristics such as rheological can predict its stability in the application matrix; however, not only should the characterization of a nanocomposite with applications in food be considered, but also the biological impact that it may present.

A novel petasin-modified zinc oxide eugenol sealer

Objective

Zinc oxide eugenol (ZOE) is one of the most commonly used root canal sealer. However, it has few drawbacks such as cytotoxicity, solubility, and irritation to periapical tissues. The scope of this study was to investigate the setting time, solubility, cytotoxic effects, and anti-inflammatory action of ZOE sealer with the modification of its liquid component by the addition of petasin extract in the ratios 1:1, 5:1, and 10:1.

Materials and Methods

Setting time was evaluated using the Vicat's apparatus. For testing solubility, the American Dental Association's specification #8 was adopted with certain modifications. Protein denaturation assay and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide assay with L929 mouse fibroblast cell lines were used to evaluate the anti-inflammatory property and cytotoxicity, respectively.

Results

ZOE sealer with petasin extract in the ratio of 5:1 showed the least initial and the final setting times. There was no statistically significant difference in the amount of solubility for all the groups at the various time intervals. The cytotoxicity of the control group was significantly greater than all the experimental groups, whereas the anti-inflammatory effect of the former was statistically lower.

Conclusions

The combination of ZOE with petasin extract in the ratio of 5:1 showed lower setting time, cytotoxicity, and better anti-inflammatory property.

Cytotoxic evaluation of a new ceramic-based root canal sealer on human fibroblasts

Objectives:

The purpose of this study was to evaluate the cytotoxicity of a new bioceramic-based root canal sealer (BioMM) by direct and indirect contact with human fibroblasts and to compare it with a zinc oxide-eugenol sealer, the Pulp Canal Sealer-extended working time (PCS-EWT).

Materials and Methods:

Cell viability was assessed through direct and indirect contact between human fibroblasts and sealer. Direct contact was performed at 24 h, whereas the indirect contact was performed at 24 and 48 h at different concentrations: 100%, 50%, and 25%. After direct contact, 3-4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was used and the optical density was measured by a spectrophotometer. Giemsa stain was also performed for a qualitative evaluation of the cells.

Statistical Analysis Used:

Shapiro–Wilk test was used to verify the normality of distribution of the variable. Data were analyzed by analysis of variance and Tukey tests using SPSS for Windows software 18.0. The significance level used was P < 0.05.

Results:

Direct contact showed a significantly higher cell viability with BioMM as compared to PCS-EWT (P = 0.002). Cell viability at 24 h was significantly higher with BioMM compared to PCS-EWT for the concentrations of 50% (P = 0.004) and 25% (P = 0.003), whereas no significant difference was noted at 100% (P = 0.141). Cell viability at 48 h was significantly higher with BioMM as compared to PCS-EWT at 25% (P = 0.007). No significant difference was observed at 100% (P = 0.484) and 50% (P = 0.185).

Conclusion:

BioMM may be considered minimally cytotoxic if accidentally extruded into the periapical tissues.

Cytotoxicity of Two Experimental Epoxy Resin-Based Sealers

INTRODUCTION

Many endodontic sealers are available, but search for the ideal sealer continues. This study aimed to assess the cytotoxicity of two experimental endodontic sealers in comparison with AH-26 resin sealer.

METHODS AND MATERIALS

This in vitro study was conducted on conventional and experimental root canal sealers: AH-26, an epoxy resin experimental sealer A (ES-A) composed of calcium tungstate, zirconium oxide, aerosil, bismuth oxide, titanium oxide, hexamine and an epoxy resin and experimental sealer B (ES-B) with compositions similar to ES-A except for the presence of imidazoline as a catalyst. The experimental sealers containing nano-particles were mixed with 37.5% of an epoxy resin. The extraction of five samples of each experimental sealer (A, B) and AH-26 sealer were subjected to MTT assay in the form of set and fresh at 1, 24 and 72 h with 1, 10, 100% dilution according to the International Standard ISO:10993-2012. Data were analyzed using the one-way ANOVA.

RESULTS

The set ES-A had the least cytotoxicity from the first hour but the cytotoxicity of ES-B and AH-26 extraction decreased over time. In fresh form, except for 100% concentration, ES-A showed the least cytotoxicity compared to the other two sealers.

CONCLUSION

All three sealers had high cytotoxicity in 100% concentration but had low cytotoxicity in 10% and 1% concentrations.

In Vitro Cytotoxicity of a New Nano Root Canal Sealer on Human Gingival Fibroblasts

Introduction:

The aim of this in vitro study was to evaluate the cytotoxicity of a new nano zinc-oxide eugenol (NZOE) sealer on human gingival fibroblasts (HGFs) compared with Pulpdent (micro-sized ZOE sealer) and AH-26 (resin-based sealer).

Methods and Materials:

The Pulpdent, AH-26, and NZOE sealers were prepared and exposed to cell culture media immediately after setting, and 24 h and one week after setting. Then, the primary cultured HGFs were incubated for 24 h with different dilutions (1:1 to 1:32) of each sealer extract. Cell viability was evaluated by methyl thiazolyl diphenyl tetrazolium bromide (MTT) assay. The results were compared using two-way analysis of variance followed by Tukey’s post hoc test. The level of significance was set at 0.05.

Results:

All sealer extracts, up to 32 times dilutions, showed cytotoxicity when exposed to HGF immediately after setting. The extracts obtained 24 h or one week after setting showed lower cytotoxicity than extracts obtained immediately after setting. At all setting times, NZOE showed lower cytotoxicity than Pulpdent and AH-26. While one-week extracts of NZOE had no significant effect on the viability of HGF at dilutions 1:4 to 1:32, both Pulpdent and AH-26 decreased the cell viability at dilutions of 1:4 and 1:8.

Conclusion:

NZOE exhibited lower cytotoxicity compared to Pulpdent and AH-26 on HGF and has the potential to be considered as a new root canal filling material.

A Comparative Evaluation of the Effect of the Addition of Pachymic Acid on the Cytotoxicity of 4 Different Root Canal Sealers-An In Vitro Study

INTRODUCTION

Root canal sealers exhibit varying degrees of cytotoxicity to periapical tissues. This in turn results in inflammation, delayed wound healing, and even bone resorption. This study aimed to explore the effect of the addition of an antioxidant like pachymic acid on the cytotoxicity of 4 root canal sealers, namely, Tubliseal (Kerr, Romulus, MI), a zinc oxide eugenol-based sealer; AH Plus (Dentsply De Trey GmbH, Konstanz, Germany), an epoxy resin-based sealer; Sealapex (Kerr), a calcium hydroxide-based sealer; and EndoREZ (Ultradent Products, South Jordan, UT), a methacrylate resin-based sealer.

METHODS

Sealers mixed according to the manufacturers' instructions formed the experimental groups. Subgroups were determined based on the absence (subgroup A) or addition (subgroup B) of pachymic acid. The experimental sealers were added to L929 mouse fibroblast cells immediately after mixing. Cell viability was evaluated by methylthiazoletetrazolium assay after 24 hours. Data were analyzed using 1-way analysis of variance. Intergroup comparisons were performed using the Kruskal-Wallis test, and intragroup comparisons were done using independent t and post hoc tests.

RESULTS

All 4 sealers were cytotoxic but to varying degrees. In both the subgroups, Sealapex exhibited the lowest cytotoxicity followed by AH Plus, Tubliseal, and EndoREZ (P < .05). The addition of pachymic acid reduced the cytotoxicity of all the sealers except that of EndoREZ (P > .05).

CONCLUSIONS

Calcium hydroxide-based Sealapex showed the least cytotoxicity compared with the other sealers. Pachymic acid could be a viable therapeutic agent to overcome the potential adverse effects associated with root canal sealers.

Inhibiting the role of Skp2 suppresses cell proliferation and tumorigenesis of human gastric cancer cells via the upregulation of p27kip1

Gastric cancer is a malignant disease of the digestive system with high rates of incidence and mortality. S‑phase kinase‑associated protein 2 (Skp2) is a novel oncogene, which has been identified to be important in tumor progression and metastasis. In order to clarify the role of Skp2 in human gastric cancer, the present study detected the expression of Skp2 in human gastric cancer tissues, and investigated the molecular mechanism of Skp2 in the progression of gastric carcinoma. The results of the initial bioinformatics analysis showed that Skp2 was significantly upregulated in 31 specimens of primary gastric cancer from a UK patient cohort, and in 10 gastric cancer lines of a side population, compared with normal gastric tissues (P<0.01). Specimens from 47 patients with gastric cancer and 19 normal gastric tissue specimens were obtained and analyzed using western blot analysis. The positive rate of expression of Skp2 was 87.2%, indicating that the expression of Skp2 was observed in 41 specimens of the detected gastric cancer samples, whereas the positive rate of the expression of Skp2 was 5.6% in the normal gastric samples (P<0.01). In the human gastric cancer cell lines, the defective regulation of Skp2 or presence of an Skp2 inhibitor inhibited the proliferation of BGC‑823 and MKN‑45 cells. In addition, the Skp2 inhibitor suppressed the proliferation of gastric cancer cells in a time‑ and dose‑dependent manner. Furthermore, transfection with Skp2 short hairpin (sh)RNA or treatment with SKP inhibitor C1 for 48 and 72 h led to the accumulation of p27kip1 in Hela cells. Tumorigenicity experiments involving nude mice showed that interference of the expression of Skp2 inhibited the growth of the human gastric tumor cells in the nude mice, and the tumor weights and volumes in the Skp2 shRNA group were significantly lower, compared with those in the negative control shRNA group (P<0.01) and untreated group (P<0.01). Taken together, these data suggested that Skp2 acted as an oncogene in human gastric cancer, and that Skp2‑mediated p27kip1 degradation contributed to the progression of gastric cancer. Abrogating the effects of Skp2 may effectively inhibit the growth of gastric cancer cells, which may be useful as a novel target in the clinical treatment of gastric cancer.

Regulatory elements of stx2 gene and the expression level of Shiga-like toxin 2 in Escherichia coli O157:H7

BACKGROUND/PURPOSE

Shiga-like toxin (Stx) is an important factor in the pathogenesis of Escherichia coli O157:H7 infection and is responsible for some severe complications. Stx2 is usually associated with hemolytic uremic syndrome in humans. Its expression is regulated by elements located upstream of the stx2 gene, including stx2-promoter sequence, ribosome binding site, and the antiterminator q gene. The present study aimed to find the correlation between regulatory elements and the expression level of Stx2 in two local isolates of E. coli O157:H7.

METHODS

Two local E. coli O157:H7 strains SM-25(1) and KL-48(2), originating from human and cattle feces, respectively, and an E. coli reference strain, ATCC 43894, were investigated. The complete stx2 gene covering the sequences of promoter, ribosome binding site, and open reading frame and q gene of each strain was analyzed. The magnitude of Stx2 production was detected with a reverse passive latex agglutination method and Stx mediated cellular damage was determined with the Vero cell assay.

RESULTS

A comparison of the complete stx2 gene contained stx2-promoter, ribosome binding site, and q genes of two local strains KL-48(2) and SM25(1), and the E. coli ATCC 43894 showed that the amino acid sequences were identical. Both local isolates were Stx negative in the reverse passive latex agglutination test and nontoxic in the Vero cell assay.

CONCLUSION

The expression level of Shiga-like toxin of the two local isolates of E. coli O157:H7 did not only depend on the regulatory elements of the stx2 gene.

The effects of Sarconesiopsis magellanica larvae (Diptera: Calliphoridae) excretions and secretions on fibroblasts

Sarconesiopsis magellanica is a necrophagous blowfly which is relevant in both forensic and medical sciences. Previous studies regarding this species have led to understanding life-cycle, population and reproduction parameters, as well as identifying and characterising proteolytic enzymes derived from larval excretions and secretions (ES). As other studies have shown that ES proteolytic activity plays a significant role in wound healing and fibroblasts play a relevant role in granulation tissue formation during such healing, the present study was aimed at analysing the biological effect of S. magellanica larval ES on fibroblasts. ES were obtained from third-instar larvae and added to fibroblast cells at three concentrations (10, 5 and 1 μg/mL) to evaluate their behaviour. MTT assays were used for analysing cell proliferation and viability, whilst cell adhesion was measured by optical density with 10% SDS. Fibroblast migration and morphology was recorded by microscopic observation. ES did not affect fibroblast viability and induced an increase in cell proliferation; cell adhesion became reduced, whilst cell migration through extracellular matrix increased. ES also induced a decreased cell surface and morphological alterations. Changes in all the above-mentioned parameters were reduced when ES were incubated at 60 °C, probably due to protease denaturation. These results suggested that the proteases contained in S. magellanica larval ES contributed towards granulation tissue formation, increased cell migration and promoted cell proliferation. All these data support carrying out further experiments aimed at validating S. magellanica usefulness in larval therapy.

Structure- and concentration-specific assessment of the physiological reactivity of α-dicarbonyl glucose degradation products in peritoneal dialysis fluids

In peritoneal dialysis (PD), glucose degradation products (GDPs), which are formed during heat sterilization of dialysis fluids, lead to structural and functional changes in the peritoneal membrane, which eventually result in the loss of its ultrafiltration capacity. To determine the molecular mechanisms behind these processes, the present study tested the influence of the six major α-dicarbonyl GDPs in PD fluids, namely, glyoxal, methylglyoxal, 3-deoxyglucosone (3-DG), 3-deoxygalactosone (3-DGal), 3,4-dideoxyglucosone-3-ene (3,4-DGE), and glucosone with respect to their potential to impair the enzymatic activity of RNase A as well as their effects on cell viability. For comprehensive risk assessment, the α-dicarbonyl GDPs were applied separately and in concentrations as present in conventional PD fluids. Thus, it was shown that after 5 days, glucosone impaired RNase A activity most distinctly (58% remaining activity, p < 0.001 compared to that of the control), followed by 3,4-DGE (62%, p < 0.001), 3-DGal (66%, p < 0.001), and 3-DG (76%, p < 0.01). Methylglyoxal and glyoxal caused weaker inactivation with significant effects only after 10 days of incubation (79%, 81%, p < 0.001). Profiling of the advanced glycation end products formed during the incubation of RNase A with methylglyoxal revealed predominant formation of the arginine modifications imidazolinone, CEA/dihydroxyimidazoline, and tetrahydropyrimidine at Arg10, Arg33, Arg39, and Arg85. Particularly, modification at Arg39 may severely affect the active site of the enzyme. Additionally, structure- and concentration-specific assessment of the cytotoxicity of the α-dicarbonyl GDPs was performed. Although present at very low concentration, the cytotoxic effect of PD fluids after 2 days of incubation was exclusively caused by 3,4-DGE (14% cell viability, p < 0.001). After 4 days of incubation, 3-DGal (13% cell viability, p < 0.001), 3-DG (24%, p < 0.001), and, to a lower extent, glyoxal and methylglyoxal (both 57%, p < 0.01) also reduced cell viability significantly. In conclusion, 3,4-DGE, 3-DGal, and glucosone appear to be the most relevant parameters for the biocompatibility of PD fluids.

A comparative study on root canal repair materials: a cytocompatibility assessment in L929 and MG63 cells

Cytocompatibility of repair materials plays a significant role in the success of root canal repair. We conducted a comparative study on the cytocompatibility among iRoot BP Plus, iRoot FS, ProRoot MTA, and Super-EBA in L929 cells and MG63 cells. The results revealed that iRoot FS was able to completely solidify within 1 hour. iRoot BP Plus required 7-day incubation, which was much longer than expected (2 hours), to completely set. ProRoot MTA and Super-EBA exhibited a similar setting duration of 12 hours. All the materials except Super-EBA possessed negligible in vitro cytotoxicity. iRoot FS had the best cell adhesion capacity in both L929 and MG63 cells. With rapid setting, negligible cytotoxicity, and enhanced cell adhesion capacity, iRoot FS demonstrated great potential in clinical applications. Future work should focus on longer-term in vitro cytocompatibility and an in vivo assessment.