A critical analysis of research methods and experimental models to study biocompatibility of endodontic materials

Biological Effects of New Chemical-Mechanical Caries Removal Products on Human Dental Pulp Stem Cells

INTRODUCTION

The aim of this study was to compare the biological effects of four chemical caries removal materials and to assess their cytotoxicity using human dental pulp stem cells (hDPSCs).

METHODS

The products evaluated are: 1 - papain-based product (BRIX 3000®); 2 - papain/chloramine based products (NATURAL-CARE and Papacárie Duo®); and 3 - chloramine based product (Cariesolut). The following in vitro experiments were carried out: IC50 measurement, cell metabolic activity (MTT) assay, cell migration, immunofluorescence experiment, cell apoptosis analysis, and reactive oxygen species (ROS) production analysis. Statistical analyses were performed using one-way ANOVA followed by Tukey's post hoc test (p < 0.05).

RESULTS

The IC50 values were: Brix 3000: 0.596%; Papacárie Duo: 0.052%; NATURAL CARE: 1.034%; and Cariesolut: 0.020%. The MTT assays showed non-adequate cell viability of all chemical-mechanical caries removal tested at 2% at 24, 48, and 72 h (p < 0.001). The same behaviour was observed at 0.1% in the Papacárie Duo and Cariesolut groups. In contrast, 0.1% of Brix 3000 at all times and NATURAL CARE at 24 h treated cells showed cell viability rates similar to the control group. At 0.01% only Brix 3000 did not show statistically significant differences at any time. Delayed cell migration was observed in all hDPSCs treated with Papacárie Duo and Cariesolut (p < 0.01 and p < 0.001). Phalloidin staining images showed a high confluence of cells in the presence of NATURAL CARE, similar to the control group. On the contrary, no cells were observed in Brix 3000 and Cariesolut at 2% and 0.1% concentrations. Papacárie Duo showed cells at all concentrations, but hDPSCs treated at 0.01% concentration exhibited better proliferation and spreading than those in the control group. Apoptosis essay showed that Brix 3000 at both 0.1% and 0.01% had a percentage of live cells higher than 99%, with 68.4% live cells at 2%, 3.69% early apoptotic cells, and 27.9% late apoptotic cells. Conversely, the rest of the materials showed an abundance of apoptotic cells, even at low concentrations. 0.1% and 0.01% of BRIX 3000 did not affect the ROS production levels, while 2% of BRIX 3000 counterpart very significantly increased the percentage of CM-H2DCFDA positive cells. Again, all concentrations of Cariesolut showed significantly higher levels of ROS production than those observed in control cells.

CONCLUSION

Our results suggest that Brix 3000 would be the most suitable material for chemical caries removal, with Papacárie Duo and NATURAL CARE also being good options, and discourage the use of Cariesolut due to its low cytocompatibility on dental pulp stem cells.

In silico assessment of biocompatibility and toxicity: molecular docking and dynamics simulation of PMMA-based dental materials for interim prosthetic restorations

AIM

This study aimed to comprehensively assess the biocompatibility and toxicity profiles of poly(methyl methacrylate) (PMMA) and its monomeric unit, methyl methacrylate (MMA), crucial components in dental materials for interim prosthetic restorations.

METHODOLOGY

Molecular docking was employed to predict the binding affinities, energetics, and steric features of MMA and PMMA with selected receptors involved in bone metabolism and tissue development, including RANKL, Fibronectin, BMP9, NOTCH2, and other related receptors. The HADDOCK standalone version was utilized for docking calculations, employing a Lamarckian genetic algorithm to explore the conformational space of ligand-receptor interactions. Furthermore, molecular dynamics (MD) simulations over 100 nanoseconds were conducted using the GROMACS package to evaluate dynamic actions and structural stability. The LigandScout was utilized for pharmacophore modeling, which employs a shape-based screening approach to identify potential ligand binding sites on protein targets.

RESULTS

The molecular docking studies elucidated promising interactions between PMMA and MMA with key biomolecular targets relevant to dental applications. MD simulation results provided strong evidence supporting the structural stability of PMMA complexes over time. Pharmacophore modeling highlighted the significance of carbonyl and hydroxyl groups as pharmacophoric features, indicating compounds with favorable biocompatibility profiles.

CONCLUSION

This study underscores the potential of PMMA in dental applications, emphasizing its structural stability, molecular interactions, and safety considerations. These findings lay a foundation for future advancements in dental biomaterials, guiding the design and optimization of materials for enhanced biocompatibility. Future directions include experimental validation of computational findings and the development of PMMA-based dental materials with improved biocompatibility and clinical performance.

A three-dimensional cell culture approach to investigate cytotoxic effects and production of inflammatory mediators by epoxy resin-based and calcium silicate-based endodontic sealer

OBJECTIVES

The aim of the present study was to assess the cytocompatibility of epoxy resin-based AH Plus Jet (Dentsply De Trey, Konstanz, Germany), Sealer Plus (MK Life, Porto Alegre, Brazil), calcium silicate-based Bio-C Sealer (Angelus, Londrina, PR, Brazil), Sealer Plus BC (MK Life) and AH Plus BC (Dentsply) through a tridimensional (3D) culture model of human osteoblast-like cells.

METHODS

Spheroids of MG-63 cells were produced and exposed to fresh root canal sealers extracts by 24 h, and the cytotoxicity was assessed by the Lactate Dehydrogenase assay (LDH). The distribution of dead cells within the microtissue was assessed by fluorescence microscopy, and morphological effects were investigated by histological analysis. The secreted inflammatory mediators were detected in cell supernatants through flow luminometry (XMap Luminex).

RESULTS

Cells incubated with AH Plus Jet, AH Plus BC, Sealer Plus BC and Bio-C Sealer extracts showed high rates of cell viability, while the Sealer Plus induced a significant reduction of cell viability, causing reduction on the spheroid structure. Sealer Plus and Seaker Plus BC caused alterations on 3D microtissue morphology. The AH Plus BC extract was associated with the downregulation of secretion of pro-inflammatory cytokines IL-5, IL-7, IP-10 and RANTES.

CONCLUSIONS

The new AH Plus BC calcium silicate-based endodontic sealer did not reduce cell viability in vitro, while led to the downregulation of pro-inflammatory cytokines.

CLINICAL SIGNIFICANCE

Choosing the appropriate endodontic sealer is a crucial step. AH Plus BC demonstrated high cell viability and downregulation of pro-inflammatory cytokines, appearing reliable for clinical use, while Sealer Plus presented lower cytocompatibility.

Novel Insights in the Hypertension Treatment & Type 2 Diabetics Induced by Angiotensin Receptor Blockers: MD Simulation Studies & Molecular Docking of Some Promising Natural Therapies

Angiotensin receptor blockers (ARBs) are commonly used to treat hypertension that target the hormonal system (renin-angiotensin system (RAS)), which regulates various physiological functions in the body. ARBs work by blocking the binding of angiotensin II to its receptor, thereby preventing a rise in blood pressure. These drugs not only normalize the overactivation of RAS but also provide protective effects against cardiovascular, renal, and type 2 diabetic patients. Inappropriate RAS activity has been linked to insulin resistance of type 2 diabetes. Olmesartan, as an ARB, was found to have a beneficial role in reducing postprandial glucose levels in type 2 diabetes. However, ARBs can cause side effects, prompting a search for new compounds that have fewer adverse effects. This study explores the potential of natural metabolites, specifically eugenol, gallic acid, myricetin, p-cymene, quercetin, and kaempferol, as ARB inhibitors compared to the current standard, olmesartan. Using in silico studies, the binding affinity of these natural substances to the ARB receptor was evaluated. The results showed that myricetin and kaempferol had affinities higher than those of olmesartan, suggesting that they could serve as promising ARB inhibitors for hypertension treatment. These natural compounds could provide an alternative approach to conventional antihypertensive drugs, which may have fewer side effects. However, more research is needed to validate the efficacy and safety of these natural compounds as antihypertensive drugs. Further in vitro and in vivo studies are needed to confirm their effectiveness and safety. This study provides a promising starting point for future investigations into the potential of natural metabolites as alternative treatments for hypertension. The findings also highlight the importance of exploring natural alternative treatments for hypertension and the protective effects of ARBs on early stage type-2 diabetics.

Premixed calcium silicate-based root canal sealers have better biological properties than AH Plus: A systematic review and meta-analysis of in vivo animal studies and in vitro laboratory studies

Objectives

The aim was to determine whether premixed calcium silicate-based root canal sealers have better biological properties than AH Plus.

Materials and Methods

Searches of studies published up to January 2023 were performed in the PubMed/MEDLINE and EMBASE and via other methods (databases of the International Endodontic Journal, Journal of Endodontics, and gray literature). The inclusion criteria were in vivo animal and in vitro studies that analyzed the response in the dorsal subcutaneous tissue of rats, cell viability, and genotoxicity. Systematic Review Centre for Laboratory Animal Experimentation Risk of Bias (RoB) tool for in vivo studies and modified CONSORT checklist for in vitro were appraised. Meta-analysis was performed using the Stata.

Results

Fifty-two studies were included. In the RoB, in vivo studies fulfilled 20%-50% of the items and in vitro 60%-100%. The studies included in the meta-analysis demonstrated better histocompatibility with the premixed calcium silicate-based sealers at 30 days and greater cell viability with these sealers when used in undiluted extracts in experimental period of 72 h and in extracts with 1:2 and 1:4 dilution in 24 and 72 h. In contrast, no difference between materials was found concerning genotoxicity.

Conclusion

Premixed calcium silicate-based root canal sealers have better histocompatibility and are less cytotoxic than the epoxy resin-based sealer AH Plus, demonstrating favorable biological behavior.

Physicochemical properties of calcium silicate cement based endodontic sealers

AIM

To mensure the physicochemical properties of three ceramic cement endodontic sealers AH Plus Bioceramic, Bio-C Sealer and Bio-C Sealer Ion+ with an epoxy resin sealer, AH Plus.

MATERIAL AND METHODS

These properties were measured: hardening time (HT), dimensional change (DC), solubility (SL), flow (FL) and radiopacity (RD). The distilled water obtained from the SL test was analyzed with atomic absorption spectrometry. A sample calculation was made considering n = 5 repetitions for each experimental sealer evaluated. Statistical analysis was performed using one-way ANOVA and post hoc Tukey tests (p < 0.05).

RESULTS

For the HT, AH Plus (484 ± 2.76 min) and AH Plus Bioceramic (424 ± 1.23 min) set more slowly than of Bio-C Sealer (370 ± 4.50 min) and Bio-C Sealer Ion+ (380 ± 1.42 min) (p < 0.05). AH Plus Bioceramic (12.56 ± 2.71 %) was more soluble than Bio-C Sealer (6.69 ± 1.67 %), Bio-C Sealer Ion+ (5.67 ± 2.16 %) and AH Plus (0.15 ± 0.01 %) (p < 0.05). AH Plus (0.03 ± 0.01 %) had slight expansion while the cement-based sealers had shrinkage: AH Plus Bioceramic (-1.60 ± 0.63 %) and Bio-C Sealer (-1.38 ± 0.69 %), Bio-C Sealer Ion+ (-5.19 ± 1.23 %) (p < 0.05). Bio-C Sealer Ion+ (59.80 ± 0.86 mm) and Bio-C Sealer (58.60 ± 0.98 mm) had the highest flow compared with AH Plus (56.90 ± 0.56 mm) and AH Plus Bioceramic (49.50 ± 0.63 mm) (p < 0.05). AH Plus (9.17 ± 0.06 mmAl) and AH Plus Bioceramic (8.27 ± 0.84 mmAl) showed radiopacity values when compared with those of Bio-C Sealer (4.90 ± 0.08 mmAl) and Bio-C Sealer Ion+ (4.14 ± 0.05 mmAl) (p > 0.05).

CONCLUSION

Ion release is inhered to these cement-based sealers and this result in calcium ion release.

In silico toxicity and immunological interactions of components of calcium silicate-based and epoxy resin-based endodontic sealers

OBJECTIVES

The present study aimed to determine in silico toxicity predictions of test compounds from hydraulic calcium silicate-based sealers (HCSBS) and AH Plus and computationally simulate the interaction between these substances and mediators of periapical inflammation via molecular docking.

MATERIALS AND METHODS

All chemical information of the test compounds was obtained from the PubChem site. Predictions for bioavailability and toxicity analyses were determined by the Molinspiration Cheminformatics, pkCSM, ProTox-II and OSIRIS Property Explorer platforms. Molecular docking was performed using the Autodock4 AMDock v.1.5.2 program to analyse interactions between proteins (IL-1β, IL-6, IL-8, IL-10 and TNF-α) and ligands (calcium silicate hydrate, zirconium oxide, bisphenol-A epoxy resin, dibenzylamine, iron oxide and calcium tungstate) to establish the affinity and bonding mode between systems.

RESULTS

Bisphenol-A epoxy resin had the lowest maximum dose tolerated in humans and was the test compound with the largest number of toxicological properties (hepatotoxicity, carcinogenicity and irritant). All systems had favourable molecular docking. However, the ligands bisphenol-A epoxy resin and dibenzylamine had the greatest affinity with the cytokines tested.

CONCLUSION

In silico predictions and molecular docking pointed the higher toxicity and greater interaction with mediators of periapical inflammation of the main test compounds from AH Plus compared to those from HCSBS.

CLINICAL RELEVANCE

This is the first in silico study involving endodontic materials and may serve as the basis for further research that can generate more data, producing knowledge on the interference of each chemical compound in the composition of different root canal sealers.

Genotoxicity induced by endodontic sealers: A systematic review

Introduction

This systematic review aimed to help further elucidate the following question: are endodontics sealers able to induce DNA damage in vitro or in vivo?

Methods

This study was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement 2020 criteria. A total of 23 studies were carefully selected by the authors.

Results

Regarding the general characteristics, most studies evaluated, on average, 3-5 types of sealers (resin epoxy, salicylate, salicylate + MTA, zinc oxide-eugenol, bioceramic products, calcium hydroxide), performing comparisons between them. Our results demonstrate that endodontic sealers may be a genotoxic agent since most studies demonstrated positive findings, with the resin-based ones being the most potentially genotoxic.

Conclusion

The type of genotoxicity assay, material evaluated, and dilution concentration levels influenced the outcome. This study clarifies whether and to what extent endodontic sealers are capable of inducing DNA injury in oral tissues.

Evaluation of the genotoxicity, cytotoxicity, and bioactivity of calcium silicate-based cements

BACKGROUND

As calcium silicate-based cements (CSCs) have found success in various vital pulp therapy applications, several new CSC products have emerged. This study aimed to assess the genotoxicity, cytotoxicity, and bioactivity of four CSCs by comparing the newly introduced materials Bio MTA+ and MTA Cem with previously studied materials, Biodentine and NeoMTA.

METHODS

Genotoxicity was evaluated using the micronucleus (MN) assay in human peripheral blood lymphocyte cells, measuring MN frequency and nuclear division index (NDI). Cytotoxicity was assessed in human dental pulp stem cells through the Water-Soluble Tetrazolium Salt-1 (WST-1) colorimetric assay. Bioactivity was determined by ELISA, measuring the levels of angiogenic and odontogenic markers (BMP-2, FGF-2, VEGF, and ALP). Statistical analyses included ANOVA, Dunnet and Sidak tests, and Wald chi-square test. (p < .05).

RESULTS

The MN frequency in the groups was significantly lower than that in the positive control group (tetraconazole) (p < .05). NDI values decreased with increasing concentration (p < .05). Bio MTA+ and NeoMTA showed decreased cell viability at all concentrations in 7-day cultures (p < .01). All materials increased BMP-2, FGF-2, and VEGF levels, with Biodentine and NeoMTA showing the highest levels of BMP-2 and FGF-2 on day 7. Biodentine displayed the highest VEGF levels on day 7. Biodentine and NeoMTA groups exhibited significantly higher ALP activity than the Bio MTA+ and MTA Cem groups by day 7.

CONCLUSION

Bio MTA+ and MTA Cem demonstrated no genotoxic or cytotoxic effects. Moreover, this study revealed bioactive potentials of Bio MTA+ and MTA Cem by enhancing the expression of angiogenic and osteogenic growth factors.

Research methods assessing sodium hypochlorite cytotoxicity: A scoping review

Sodium hypochlorite (NaOCl) cytotoxicity has been assessed using different methodologies, which has led to arbitrary interpretations. This scoping review aimed to discuss the different methodological protocols for assessing NaOCl cytotoxicity. A literature review performed in the PubMed and Embase databases up to July 2023 identified manuscripts reporting NaOCl cytotoxicity. The dataset identified 546 publications, further screened by 2 reviewers. Ninety studies were identified and mined methodologically to collect information on cell type, cytotoxicity assay, NaOCl dilution solutions, presence of fetal bovine serum (FBS), and NaOCl exposure time. The culture medium used in cytotoxicity assays contains buffering substances that neutralize the pH of NaOCl, thus reducing its cytotoxicity, an approach that may lead to bias when solutions with different pH are compared. For short exposure periods, as in simulations to evaluate the contact between irrigant and periapical tissue cells during chemo-mechanical preparation, NaOCl dilution should be performed with saline, which does not buffer the irrigant. For long exposure periods, as in simulations of irrigant extrusions, NaOCl should be diluted in the culture medium, to reproduce the expected buffering effect occurring in extrusions. The presence of FBS in culture medium can decrease NaOCl toxicity. There is no standardization of NaOCl cytotoxicity methodologies. This poses the risk of arriving at incorrect results and, therefore, pertinent tests must be refined.

Modern methods and materials used to treat root perforation: effectiveness comparison

This study aims to experimentally compare the efficacy of different endodontic materials (iRoot BP Plus, Biodentine, MTA, Rootdent, and Trioxide) in the treatment of pulpitis and perforations on extracted tooth specimens. Additionally, the study aims to investigate the influence of iRoot BP Plus endodontic material on the regenerative processes following pulp amputation in laboratory animals. The secondary goal is to evaluate the effect of iRoot BP Plus on the restoration process in laboratory animals after pulp removal. The study presents a micropermeability analysis of the selected biomaterials performed on a sample of 50 single-rooted apical teeth in 2022. All teeth underwent endodontic treatment. Changes in molar morphology were investigated with eight laboratory animals (rabbits, 3 months old, all males) after simulated pulp removal and subsequent treatment with the iRoot BP Plus biomaterials. iRoot BP Plus appeared to be more effective in retrograde apical root filling than other biomaterials, as evidenced by its higher sealing effect. An experiment involving animal participants revealed the presence of protective adaptive mechanisms, which manifested in the form of an inflammatory process within 6 weeks after the dental pulp was removed. The connective tissue replaced the necrosis, and new capillaries began to form intensively. These dental outcomes suggest that iRoot BP Plus enables hermetical sealing in tooth restoration with good adhesion. Thus, it may have the ability to promote more active tissue regeneration after pulp removal.

Novel Antibacterial and Biocompatible Nanostructured Gels Based on One-step Synthesis as a Potential Disinfectant for Endodontic Infection Control

AIM

The objective of this study was to develop nanostructured gels as biocompatible intracanal disinfectants by one-step microwave radiation-assisted synthesis.

METHODS

Polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) were used as a support network, and polyethylene glycol (PEG) was used as a reducing agent. The gels were characterized by measuring the swelling ratio (SR) and rheological properties and by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM). The antibacterial effects of each gel were evaluated against the endodontic clinical strain Enterococcus faecalis. Then, the viability of the 21-day mature multispecies bacterial biofilm was assessed using confocal microscopy in an ex vivo model, where the biofilm was exposed to the mix of nanogels. The cell proliferation, viability, and morphology of human periodontal ligament (HPDL) cells were quantified using a real-time IncuCyte® S3 Live-Cell System. Viability was measured by confocal microscopy using an ex vivo model exposing a 21-day mature multispecies bacterial biofilm to the mix of nanogels.

RESULTS

The antibacterial activity of the gels coincided with the superficial characterization and the solubility of the gel in the growth medium. Gels with higher viscosity (327.85-980.58 Pa s), higher dissolution (42-70%SR), and lower porosity (no porosity and 611.63 nm) showed excellent antibacterial activity against E. faecalis. Despite their physicochemical characteristics, CuNPs gels showed greater effectiveness against E. faecalis.These nanostructured gels with high PVA concentrations promote HPDL cells proliferation while still exerting antibacterial properties. Mix of nanogels showed an increase non-viable cells biomass from at of application.

CONCLUSIONS

The use of biocompatible polymers influences the physicochemical, bactericidal, and cytotoxic response, making these materials potential disinfectant agents against resistant bacteria with good biocompatibility and improved HPDL cells proliferation.

Effect of Different Sealers on the Cytocompatibility and Osteogenic Potential of Human Periodontal Ligament Stem Cells: An In Vitro Study

Background: There is tendency for unavoidable sealer extrusion in some clinical cases. This might adversely affect host stem cells and affect healing. This study aimed to investigate the effect of different sealers on the cytocompatibility and osteogenic potential of human periodontal ligament stem cells (hPDLSCs). Methods: The cytotoxic effect of the extracted elutes of VDW.1Seal (VDW.1), Endosequence BC Sealer HiFlow (ES), GuttaFlow-2 (GF), and ADSeal (AD-S) on the hPDLSCs was determined using the MTT assay. Cell proliferation and migration were assessed by the scratch wound healing assay. Osteogenic differentiation potential was assessed. Measurement of pH values and calcium ions release was performed. Results: GF had a significantly higher percentage of viable cells. The cell migration assay showed that GF demonstrated the lowest open wound area percentage. GF and AD-S showed the highest calcium nodule deposition. GF demonstrated higher ALP activity than ES. Expression of RUNX2 and OC genes was similar for all sealers, while OPG gene expression was significantly higher for VDW.1 and GF. ES and AD-S displayed the highest pH values on day 1. Calcium ion release of ES and VDW.1 was significantly the highest. Conclusions: GuttaFlow-2 and VDW.1Seal sealers have favorable behavior toward host stem cells.

Real-time evaluation of the biocompatibility of calcium silicate-based endodontic cements: An in vitro study

INTRODUCTION

An ideal filling material should hermetically seal the communication pathways between the canal system and surrounding tissues. Therefore, during the last few years, the development of obturation materials and techniques to create optimal conditions for the proper healing of apical tissues has been a focus of interest. The effects of calcium silicate-based cements (CSCs) on periodontal ligament cells have been investigated, and promising results have been obtained. To date, there are no reports in the literature that have evaluated the biocompatibility of CSCs using a real-time live cell system. Therefore, this study aimed to evaluate the real-time biocompatibility of CSCs with human periodontal ligament cells (hPDLCs).

METHODOLOGY

hPDLC were cultured with testing media of endodontic cements for 5 days: TotalFill-BC Sealer, BioRoot RCS, Tubli-Seal, AH Plus, MTA ProRoot, Biodentine, and TotalFill-BC RRM Fast Set Putty. Cell proliferation, viability, and morphology were quantified using real-time live cell microscopy with the IncuCyte S3 system. Data were analyzed using the one-way repeated measures (RM) analysis of variance multiple comparison test (p < .05).

RESULTS

Compared to the control group, cell proliferation in the presence of all cements was significantly affected at 24 h (p < .05). ProRoot MTA and Biodentine lead to an increase in cell proliferation; there were no significant differences with the control group at 120 h. In contrast, Tubli-Seal and TotalFill-BC Sealer inhibited cell growth in real-time and significantly increased cell death compared to all groups. hPDLC co-cultured with sealer and repair cements showed a spindle-shaped morphology except with cements Tubli-Seal and TotalFill-BC Sealer where smaller and rounder cells were obtained.

CONCLUSIONS

The biocompatibility of the endodontic repair cements performed better than the sealer cements, highlighting the cell proliferation of the ProRoot MTA and Biodentine in real-time. However, the calcium silicate-based TotalFill-BC Sealer presented a high percentage of cell death throughout the experiment similar to that obtained.

Immunomodulatory Effects of Endodontic Sealers: A Systematic Review

Inflammation is a crucial step prior to healing, and the regulatory effects of endodontic materials on the immune response can influence tissue repair. This review aimed to answer whether endodontic sealers can modulate the immune cells and inflammation. An electronic search in Scopus, Web of Science, PubMed, and Google Scholar databases were performed. This systematic review was mainly based on PRISMA guidelines, and the risk of bias was evaluated by SYRCLEs and the Modified CONSORT checklist for in vivo and in vitro studies, respectively. In total, 28 articles: 22 in vitro studies, and six in vivo studies were included in this systematic review. AH Plus and AH 26 can down-regulate iNOS mRNA, while S-PRG sealers can down-regulate p65 of NF-κB pathways to inhibit the production of TNF-α, IL-1, and IL-6. In vitro and in vivo studies suggested that various endodontic sealers exhibited immunomodulatory impact in macrophages polarization and inflammatory cytokine production, which could promote healing, tissue repair, and inhibit inflammation. Since the paradigm change from immune inert biomaterials to bioactive materials, endodontic materials, particularly sealers, are required to have modulatory effects in clinical conditions. New generations of endodontic sealers could hamper detrimental inflammatory responses and maintain periodontal tissue, which represent a breakthrough in biocompatibility and functionality of endodontic biomaterials.

Bioactivity analysis of calcium silicate-based sealers and repair cements on the phenotype and cytokine secretion profile of CD14+ monocytes: An ex vivo study

AIM

This study evaluated the immune bioactivity of testing media (TM) obtained from different calcium silicate-based sealers and cements on monocyte morphology, activation, differentiation and cytokine secretion.

METHODS

Blood-derived CD14⁺ monocytes were isolated and cultured for 5 days with 25% TM from the following calcium silicate-based materials: TotalFill BC RRM Fast-Set Putty, Biodentine, TotalFill BC Sealer and BioRoot-Root-Canal-Sealer (RCS). A resin-based endodontic cement was used as a control. The expression of surface markers such as CD86, HLA-DR, CD16, CD309 and CD209, and cytokine secretion were analysed by flow cytometry. Data were analysed using the one-way repeated measures analysis of variance (anova) multiple comparison test and a Holm-Sidak multiple comparison post-hoc test (p < .05).

RESULTS

This comparative analysis revealed that monocytes co-cultured with calcium silicate-based materials showed a spindle-shaped morphology compared with the round shape observed in the control. Regarding activation markers, BioRoot-RCS and Biodentine significantly increased CD86 expression compared with the control sample, whereas no significant differences (p > .05) were observed in HLA-DR expression. In addition, no differences were observed among the differentiation markers. When the inflammatory cytokines were analysed, BioRoot-RCS increased the secretion of IL-1β, IL-6, IL-10 and TNF-α, whereas BioRoot-RCS and Biodentine significantly decreased IL-8 production (p < .05).

CONCLUSIONS

These data showed that the calcium silicate-based materials tested changed the morphology of CD14⁺ monocytes; however, only BioRoot-RCS and Biodentine significantly upregulated CD86. In addition, BioRoot-RCS was the sealer with the highest immunomodulatory properties for cytokine production which means that it can contribute with the in vivo healing process and regeneration of periapical lesions.

Biocompatibility Assessment of Two Commercial Bone Xenografts by In Vitro and In Vivo Methods

Bone substitutes based on xenografts have been used for a long time in bone regeneration thanks to their inductive capacity for bone tissue regeneration. Some bone-based scaffolds have been modified by adding collagen and other proteins to improve their regenerative capacity and prevent migration and aggregation, especially particles. However, rejection of this graft has been reported due to protein residues caused by poor material preparation. We compared the in vitro and in vivo biological response of two commercial xenografts (InterOss^®, F1 and InterOss^® Collagen, F2) and a commercial porcine collagen membrane (InterCollagen^® Guide, F3) as a rapid degradation control. Fourier Transform Infrared Spectroscopy (FT-IR) analysis evidenced the presence of hydroxyl, orthophosphate, and carbonate groups of the xenografts and amide groups of collagen. Thermogravimetric analysis (TGA) of the xenografts demonstrated their thermal stability and the presence of a few amounts of organic material. The study by differential scanning calorimetry showed the presence of endothermic peaks typical of the dehydration of the xenografts (F1 and F2) and for the collagen membrane (F3), the beginning of structural three-dimensional protein changes. Subsequently, in vitro biocompatibility tests were carried out for the materials with Artemia salina and MTT cell viability with HeLa cells, demonstrating the high biocompatibility of the materials. Finally, in vivo biocompatibility was studied by implanting xenografts in biomodels (Wistar rats) at different periods (30, 60, and 90 days). The F1 xenograft (InterOss) remained remarkably stable throughout the experiment (90 days). F2 (InterOss Collagen) presented a separation of its apatite and collagen components at 60 days and advanced resorption at 90 days of implantation. Finally, the collagen membrane (F3) presented faster resorption since, at 90 days, only some tiny fragments of the material were evident. All the in vivo and in vitro test results demonstrated the biocompatibility of the xenografts, demonstrating the potential of these materials for tissue engineering.

Cytotoxicity and Genotoxicity of Epoxy Resin-Based Root Canal Sealers before and after Setting Procedures

Epoxy resin-based sealers are commonly used for successful endodontic treatment. This study aimed to evaluate the cytotoxicity and genotoxicity of epoxy resin-based sealers under unset and set conditions. Three epoxy resin-based sealers were used: Adseal, AH Plus, and Dia-Proseal. To test cytotoxicity, an agar overlay test and a 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay were performed using unset and set sealers on L929 mouse fibroblasts. The genotoxicity test of the comet assay was performed using the same cell line. Extract dilutions in the culture media were used as test materials for the MTT and comet assays. The comet tail produced by the damaged DNA was calculated by image analyses. Statistical analyses were performed using one-way analysis of variance and Tukey’s post hoc test. Unset sealers did not show defined decolorized areas. Hardened specimens of resin-based sealers showed circular discolored zones in the agar overlay test. Dia-Proseal was the least cytotoxic after hardening. These results were confirmed in the MTT assay. Cell viability was significantly higher in cells treated with hardened sealers in both groups than that in cells treated with freshly mixed sealers in the MTT assay. Unset AH Plus^® and Dia-Proseal™ significantly increased cell viability with decreasing dilution. Adseal™ was the least cytotoxic. Freshly mixed Adseal™ was more genotoxic when freshly mixed than when set. Unset epoxy resin-based sealers were generally more cytotoxic and genotoxic than set materials. Cytotoxicity does not always match the genotoxicity results; therefore, various test tools are required to test toxicity. It is necessary to properly evaluate the toxic effects to establish a biocompatibility test that mimics clinical conditions.

The influence of methodology on the comparison of cytotoxicity of total-etch and self-etch adhesive systems

OBJECTIVES

The present study aimed to compare the in vitro cytocompatibility of two etch-and-rinse (Adper Scothbond, Optibond) and two self-etch (Clearfill SE Bond and Single Bond Universal) dental adhesives through a dentin-barrier model with human pulp fibroblasts.

METHODS

Human fibroblasts were placed on a plastic device containing 500μm human dentin discs treated with each adhesive or without treatment (control). Other groups were directly exposed to media conditioned with adhesive samples according to ISO 10993-5:2009. After 24h exposure, cell viability was assessed by XTT, and released inflammatory mediators were detected with a multiparametric immunoassay.

RESULTS

The standardized test without barrier indicated both etch-and-rinse adhesives and self-etch as cytotoxic, promoting viabilities under 70% of the control group (p<0.05). The dentin-barrier model identified increased cell viability for self-etch adhesives, with Clearfill SE Bond identified as non-cytotoxic. The immunoassay evidenced high rates of cytokines by cells exposed to the conditioned media of Adper Scotchbond, Optibond S, and Single Bond Universal.

CONCLUSIONS

The use of a dentin-barrier in vitro model detected a better biocompatibility for self-etching adhesives and, in the case of Clearfill SE Bond, with a reversion from cytotoxic to biocompatible when compared to the indirect standardized test.

CLINICAL SIGNIFICANCE

The use of a dentin-barrier in vitro model was able to detect a better biocompatibility for self-etching adhesives when compared to the indirect standardized test and presents itself as a predictive in vitro method for assessing the cytotoxicity of dental restorative materials that may simulate the clinical condition more accurately.