Physical Properties and Biofunctionalities of Bioactive Root Canal Sealers In Vitro

Biological properties versus solubility of endodontic sealers and cements

Endodontic sealers and cements used in root canal treatment have different compositions and properties. Common to all materials is that their primary goal is to fill gaps and voids, making a permanent seal of the root canal system. Furthermore, aspects such as antibacterial properties, cytotoxicity, setting time, solubility and biocompatibility are also crucial and ought to be considered. Over the years, a shift in the view on the importance of these aspects has ocurred. Whereas the antibacterial properties were considered important when the technical factors in endodontics were less developed, the sealing ability and biocompatibility have later been considered the most critical factors. The introduction of tricalcium silicate cements and sealers has led to a renewed interest in material properties, as these cements seem to have good sealing ability and at the same time combine favourable antimicrobial effects with excellent biocompatibility. This review discusses how the various properties of root canal sealers and cements may conflict with the primary aim of providing a permanent seal of the root canal system.

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.

In Vitro Comparison of Differences in Setting Time of Premixed Calcium Silicate-Based Mineral Trioxide Aggregate According to Moisture Content of Gypsum

Recently, a paste-type premixed calcium silicate-based mineral trioxide aggregate (MTA) product that quickly solidifies through a pozzolanic reaction was introduced to replace existing MTA, which has the disadvantage of a long setting time. In this study, we evaluated the effect of moisture content in the root canal on the setting time of premixed calcium silicate-based MTA in a simulated root canal environment using Endoseal MTA and Well-Root ST, among commercially available products. The setting time was measured according to ISO 6876/2012. A mold made using grades 2, 3, and 4 dental gypsum according to the classification of ISO 6873/2013 was used to reproduce the difference in moisture environment. Differences in moisture content were measured using micro-computed X-ray tomography (micro-CT). The micro-CT results showed that the moisture content was the highest and lowest in the grade 2 and 4 gypsum molds, respectively. Moreover, the setting time indicated by the manufacturer was the shortest for the grade 2 gypsum mold. Hence, the differences in moisture content significantly affect the setting time of MTA. This result can help set future experimental conditions and develop premixed calcium silicate-based MTA products.

Physical-chemical properties and acellular bioactivity of newly prepared nano-tricalcium silicate-58s bioactive glass-based endodontic sealer

OBJECTIVES

To evaluate the physiochemical properties and apatite-forming ability of a newly prepared nano-tricalcium silicate-58s bioactive glass-based endodontic sealer (C3S-BG-P) and compare its results with the Nishika BG canal sealer and BioRoot™ RCS.

METHODS

The physicochemical properties (setting time, flow, solubility, film thickness, and radiopacity) of C3S-BG-P, Nishika BG canal sealer, and BioRoot™ RCS were evaluated in accordance with ANSI/ADA 57/2000 (reaffirmed 2012) and ISO 6876:2012 for root canal sealing materials. The in vitro apatite-forming ability was evaluated after 28 days of immersion of disc-shaped specimens in phosphate-buffered saline (PBS) using field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy.

RESULTS

The results of physiochemical tests indicated that all the tested sealers complied with the ADA and ISO standards; however, the solubility of the BioRoot did not meet the two standards. C3S-BG-P revealed significantly superior properties in all physicochemical tests compared to Nishika and BioRoot; however, the solubility of Nishika was significantly lower than that of C3S-BG-P. Furthermore, all tested sealers exhibited apatite precipitation on their surfaces after 28 days of immersion in PBS.

CONCLUSIONS

C3S-BG-P had superior physicochemical properties, which mitigated the disadvantages of calcium silicate-based sealers. Moreover, it exhibited apatite precipitation after immersion in PBS. Further in vivo studies utilizing animal models or clinical studies are necessary to support the rationale of the newly developed sealer for clinical application.

Chemomechanical Properties and Biocompatibility of Various Premixed Putty-type Bioactive Ceramic Cements

INTRODUCTION

This study aimed to evaluate the chemomechanical properties and biocompatibility of recently introduced premixed putty-type bioactive ceramic cements (PPBCs).

METHODS

Including ProRoot MTA (PMTA) as a control, BC RRM fast-set putty (BCPT), Well-Root PT (WRPT), One-Fil PT (OFPT), and Endocem MTA premixed (ECPM) were compared to evaluate setting time, radiopacity, pH change, and microhardness. Biocompatibility on human dental pulp cells was compared using CCK-8 assay. Mineralization potential was evaluated using alkaline phosphatase activity, Alizarin Red S (ARS) staining, and quantitative real-time polymerase chain reaction with odontogenic gene marker. For data analysis, 1-way analysis of variance and Tukey's post hoc test were used at the significance level of 95%.

RESULTS

Among the PPBCs, BCPT presented the longest (552 ± 27) setting time (minutes) and others showed significantly shorter time than PMTA (334 ± 22) (P < .05). WRPT (6.20 ± 0.54) and OFPT (5.82 ± 0.50) showed significantly higher radiopacity values (mmAl) and others showed similar value compared with PMTA (P > .05). All PPBCs showed high alkaline pH from fresh materials and tended to increase according to time periods from 30 minutes to 12 hours. ECPM showed the highest value of microhardness (81.62 ± 5.90), WRPT showed similar, and others showed lower than PMTA (P < .05). All PPBCs showed biocompatibility in CCK-8 assay. All PPBCs showed similar or better value compared with PMTA in ALP and ARS staining, and ALP and DSPP marker expression (P < .05).

CONCLUSIONS

The PPBCs showed clinically acceptable chemomechanical properties and favorable mineralization potential.

Synthesis and analyses of injectable fluoridated-bioactive glass hydrogel for dental root canal sealing

This study aimed to synthesize fluoride-doped bioactive glass (F-BG) based thermo-sensitive injectable hydrogel for endodontic applications. The structural and phase analyses were done with Fourier Transform Infrared spectroscopy and X-ray Diffraction, respectively. The setting time of prepared injectable was investigated at 21°C (in the presence and absence of an ultrasonic scalar) and at 37°C. Flowability was tested according to ISO-6876:2012 specifications, whereas injectability was checked by extrusion method using 21-, 22-, and 23-gauge needles. The in vitro bio-adhesion and push-out bond strength were studied on days 7 and 90 and compared with the commercially available TotalFill®. The ion release profile was analyzed for up to 30 days with Inductively Coupled Plasma Optical Emission Spectroscopy. The fluoride release analysis was conducted periodically for up to 21 days in deionized water and artificial saliva using an ion-selective electrode. The final setting time at 21°C, 21°C+ultrasonic scalar, and 37°C were 38.66±3.21, 29.12±1.23, and 32±3.46 min, respectively. The flowability was 25±3.94 mm, and the injectability coefficient was ≥70.3 for 22, 21, and 57% in a 23-gauge needle. Fluoride release in deionized water was found to be significantly higher than in artificial saliva and increased with time. A significant difference in bond strength was found between days 7 and 90, where the strength was increased, and a new apatite layer was formed on the tooth surface. A rapid release of calcium, phosphate, and silicon ions was seen initially, whereby the continuous release of these ions was observed for up to 30 days. The prepared F-BG injectable hydrogel has shown promising results and has the potential to be used as an endodontic sealer.

Hydraulic calcium silicate-based root canal sealers mitigate proinflammatory cytokine synthesis and promote osteogenesis in vitro

Background/purpose

The mineralized tissue-inductive ability and anti-inflammatory properties of hydraulic calcium silicate-based (HCSB) sealers have not been fully elucidated. This study aimed to evaluate the effects of the HCSB sealers Bio-C sealer (BioC), Well-Root ST (WST), and EndoSequence BC sealer (BC), on osteoblastic differentiation/mineralization and proinflammatory cytokine synthesis by macrophages.

Materials and methods

Diluted extracts of set sealers or calcium chloride solutions of approximately equivalent Ca2+ concentrations were applied to a mouse osteoblastic cell line (Kusa-A1 cells) and lipopolysaccharide-stimulated mouse macrophage cell line (RAW264.7 cells). Expressions of osteoblastic markers in Kusa-A1 cells and proinflammatory cytokines in RAW264.7 cells were evaluated by reverse transcription-quantitative polymerase chain reaction and enzyme-linked immunosorbent assays. Mineralized nodules were detected by Alizarin red S staining. Cell proliferation was assessed by WST-8 assay and cell attachment on set sealers was examined by scanning electron microscopy.

Results

The three sealer extracts significantly upregulated osteocalcin and osteopontin mRNA, and promoted significant mineralized nodule formation in Kusa-A1 cells. The three sealer extracts significantly downregulated the mRNA expressions of interleukin (IL)-1α, IL-1β, IL-6, and tumor necrosis factor (TNF)-α and protein levels of IL-6 and TNF-α in RAW264.7 cells. Calcium chloride solutions induced osteoblastic differentiation/mineralization. AH Plus Jet (a control sealer) extract did not. The three HCSB sealers did not interfere with the growth and attachment of Kusa-A1 cells.

Conclusion

BioC, WST, and BC were biocompatible, upregulated osteoblastic differentiation/mineralization, and downregulated proinflammatory cytokine expression. Ca2+ released from HCSB sealers might be involved, at least in part, in the induction of osteoblastic differentiation/mineralization.

Innovative Nanostructured Fillers for Dental Resins: Nanoporous Alumina and Titania Nanotubes

The possibility of improving dental restorative materials is investigated through the addition of two different types of fillers to a polymeric resin. These fillers, consisting of porous alumina and TiO₂ nanotubes, are compared based on their common physicochemical properties on the nanometric scale. The aim was to characterize and compare the surface morphological properties of composite resins with different types of fillers using analytical techniques. Moreover, ways to optimize the mechanical, surface, and aesthetic properties of reinforced polymer composites are discussed for applications in dental treatments. Filler-reinforced polymer composites are the most widely used materials in curing dental pathologies, although it remains necessary to optimize properties such as mechanical resistance, surface characteristics, and biocompatibility. Anodized porous alumina nanoparticles prepared by electrochemical anodization offer a route to improve mechanical properties and biocompatibility as well as to allow for the controlled release of bioactive molecules that can promote tissue integration and regeneration. The inclusion of TiO₂ nanotubes prepared by hydrothermal treatment in the resin matrix promotes the improvement of mechanical and physical properties such as strength, stiffness, and hardness, as well as aesthetic properties such as color stability and translucency. The surface morphological properties of composite resins with anodized porous alumina and TiO₂ nanotube fillers were characterized by Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), and X-ray chemical analysis. In addition, the stress-strain behavior of the two composite resins is examined in comparison with enamel and dentin.

In Vivo Assessment of the Apatite-Forming Ability of New-Generation Hydraulic Calcium Silicate Cements Using a Rat Subcutaneous Implantation Model

Hydroxyapatite formation on endodontic hydraulic calcium silicate cements (HCSCs) plays a significant role in sealing the root canal system and elevating the hard-tissue inductivity of the materials. This study evaluated the in vivo apatite-forming ability of 13 new-generation HCSCs using an original HCSC (white ProRoot MTA: PR) as a positive control. The HCSCs were loaded into polytetrafluoroethylene tubes and implanted in the subcutaneous tissue of 4-week-old male Wistar rats. At 28 days after implantation, hydroxyapatite formation on the HCSC implants was assessed with micro-Raman spectroscopy, surface ultrastructural and elemental characterization, and elemental mapping of the material-tissue interface. Seven new-generation HCSCs and PR had a Raman band for hydroxyapatite (v1 PO₄^3- band at 960 cm^-1) and hydroxyapatite-like calcium-phosphorus-rich spherical precipitates on the surfaces. The other six HCSCs with neither the hydroxyapatite Raman band nor hydroxyapatite-like spherical precipitates did not show calcium-phosphorus-rich hydroxyapatite-layer-like regions in the elemental mapping. These results indicated that 6 of the 13 new-generation HCSCs possessed little or no ability to produce hydroxyapatite in vivo, unlike PR. The weak in vivo apatite-forming ability of the six HCSCs may have a negative impact on their clinical performance.

Bioactivity Potential of Bioceramic-Based Root Canal Sealers: A Scoping Review

INTRODUCTION

Bioceramic-based root canal sealers are novel materials with a bioactivity potential that stands out compared with conventional root canal sealers. However, the term bioactivity may be overused and is often misunderstood. Hence, the objective of this study was to synthesize and map key concepts related to the bioactivity analysis of bioceramic-based root canal sealers.

METHODS

The present scoping review is reported in accordance with the PRISMA-ScR Statement and is registered in the Open Science Framework. Two blinded reviewers carried out a comprehensive search in six databases up to January 10th, 2022: MEDLINE, Scopus, Embase, Web of Science, Cochrane Library, and Lilacs/BBO. Eligibility was considered for in vitro and in vivo studies that evaluated the bioactivity potential of bioceramic-based root canal sealers.

RESULTS

A total of 53 studies were included in the qualitative synthesis. In vitro bioactivity was evaluated through the mineralization potential, formation of carbonated apatite on the surface, and the gene expression related to proteins involved in the mineralization process. Meanwhile, for in vivo studies, staining techniques associated with immunohistochemical tests were mainly used to detect mineralization on the material-host tissue interface.

CONCLUSIONS

According to the methodology used, the most prevalent methods to assess bioactivity in acellular form were the immersion of the material in Hank's balanced salt solution, followed by surface observation with scanning electron microscopy and energy dispersive X-ray. In cell cultures, the chosen method was usually Alizarin Red staining, followed by the evaluation of alkaline phosphatase enzymatic activity and the use of molecular biology tests.

Premixed Calcium Silicate-Based Root Canal Sealer Reinforced with Bioactive Glass Nanoparticles to Improve Biological Properties

Recently, bioactive glass nanoparticles (BGns) have been acknowledged for their ability to promote interactions with the periapical tissue and enhance tissue regeneration by releasing therapeutic ions. However, there have been no studies on calcium silicate sealers with bioactive glass nanoparticle (BGn) additives. In the present study, a premixed calcium silicate root canal sealer reinforced with BGn (pre-mixed-RCS@BGn) was developed and its physicochemical features and biological effects were analyzed. Three specimens were in the trial: 0%, 0.5%, and 1% bioactive glass nanoparticles (BGns) were gradually added to the premixed type of calcium silicate-based sealer (pre-mixed-RCS). To elucidate the surface properties, scanning electron microscopy, X-ray diffraction, and energy-dispersive spectroscopy were used and flowability, setting time, solubility, and radiopacity were analyzed to evaluate the physical properties. Chemical properties were investigated by water contact angle, pH change, and ion release measurements. The antibacterial effects of the bioactive set sealers were tested with Enterococcus faecalis and the viability of human bone marrow-derived mesenchymal stem cells (hMSCs) with this biomaterial was examined. In addition, osteogenic differentiation was highly stimulated, which was confirmed by ALP (Alkaline phosphatase) activity and the ARS (Alizarin red S) staining of hMSCs. The pre-mixed-RCS@BGn satisfied the ISO standards for root canal sealers and maintained antimicrobial activity. Moreover, pre-mixed-RCS@BGn with more BGns turned out to have less cytotoxicity than pre-mixed-RCS without BGns while promoting osteogenic differentiation, mainly due to calcium and silicon ion release. Our results suggest that BGns enhance the biological properties of this calcium silicate-based sealer and that the newly introduced pre-mixed-RCS@BGn has the capability to be applied in dental procedures as a root canal sealer. Further studies focusing more on the biocompatibility of pre-mixed-RCS@BGn should be performed to investigate in vivo systems, including pulp tissue.

Cytotoxicity and biocompatibility of root canal sealers: A review on recent studies

Many types of endodontic root canal sealers have been employed for the purpose of filling voids and irregularities in root canals, as well as reducing/removing bacterial remnants/remains. Sealers are available in various formulations, and research work to find the most appropriate ones is still ongoing. Recently, many kinds of novel root canal sealers have been introduced under various commercial names. However, most sealers are known to exhibit different levels of cytotoxicity on tissues which would result in prolonged wound healing, inflammation, and bone resorption. Preferably, sealers need to have tolerable biological and physico-chemical properties along with biocompatibility. Additives promoting the biocompatibility and bioactivity of sealers are of major concern in clinical applications. The aim of this review was to compare, evaluate, and analyze comparatively the cytotoxic effects, biocompatibility, and antimicrobial properties of recently used root canal sealers. A comprehensive literature search was made to identify their properties involving biocompatibility and cytotoxicity. In general, the sealers reported in recent literature exhibited favorable biological features in comparison to conventional ones. They promoted better cell viability and biocompatibility. The incorporation of additives influences favorably the potential negative effects. However, it has been highlighted that there is a lack of well-designed long-term clinical applications, and more in vitro and in vivo research work would be helpful to confirm the sustainability of the sealers for further clinical practice.

Physico-Chemical Properties of Calcium-Silicate vs. Resin Based Sealers-A Systematic Review and Meta-Analysis of Laboratory-Based Studies

INTRODUCTION

The aim of this systematic review is to analyse the effect of physico-chemical properties of calcium silicate-based sealers in comparison to epoxy resin sealers in permanent teeth using a single-cone obturation technique.

METHODS

The study was conducted according to the guidelines of Cochrane Handbook for Systematic Reviews of Interventions and Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) statement. Literature search was performed using the PubMed/MEDLINE, Cochrane Central Register of Controlled Trials, Web of Science, DOAJ, Open Gray with no language restrictions until October 2020. Two reviewers assessed the studies for eligibility. Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) was carried out to assess the evidence. Meta-analysis of the pooled data with subgroups was performed using the RevMan software (p < 0.05).

RESULTS

Results from the 28 included studies showed that the mean difference in adaptation to root canal walls (marginal adaptation, interfacial gaps and void volume) for both sealers were non-significant. However, void volume values showed a significant mean difference (p < 0.00001) favouring the calcium silicate-based sealers. The pooled meta-analysis reported statistically significant differences for apical microleakage (p = 0.0007) whilst there were non-significant mean differences for fracture resistance (p = 0.09) and push-out bond strength (p = 0.63). The heterogeneity among the included studies was 97% (I²).

CONCLUSIONS

Within the limitations of this review, calcium silicate-based sealers demonstrated a similar or superior performance in comparison to resin-based sealers in terms of the physico-chemical properties.

Evaluation of the anti-inflammatory effects of surface-reaction-type pre-reacted glass-ionomer filler containing root canal sealer in lipopolysaccharide-stimulated RAW264.7 macrophages

A prototype surface-reaction-type pre-reacted glass-ionomer (S-PRG) filler containing root canal sealer (S-PRG sealer) exhibits bioactive potential by releasing multiple ions. This study explored the suppressive effects and modes of action of S-PRG sealer extracts on proinflammatory cytokine expression in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Expression of proinflammatory cytokines was evaluated by RT-qPCR and ELISA. Expression of phosphorylated nuclear factor-kappa B (p-NF-kB) p65 was evaluated by western blotting. S-PRG sealer extracts significantly downregulated mRNA expression levels of interleukin (IL)-1α, IL-6, and TNF-α in LPS-stimulated RAW264.7 cells; the extracts also reduced the levels of IL-6 protein and p-NF-kB. In order to verify that Zn²⁺ was responsible for downregulation of proinflammatory cytokine expression, N,N,N',N'-tetrakis(2-pyridylmethyl) ethylenediamine (TPEN) was used as a heavy metal chelator with strong affinity for Zn²⁺. These effects were mitigated by TPEN. The application of ZnCl₂ reproduced the actions of S-PRG sealer extracts. These data suggest that S-PRG sealer has anti-inflammatory potential involving heavy metal ions such as Zn²⁺.

Development of a Robust Control Strategy for Fixed-Dose Combination Bilayer Tablets with Integrated Quality by Design, Statistical, and Process Analytical Technology Approach

Control strategy and quality by design (QbD) are widely used to develop pharmaceutical products and improve drug quality; however, studies on fixed-dose combination (FDC) bilayer tablets are limited. In this study, the bilayer tablet consisted of high-dose metformin HCl in a sustained-release layer and low-dose dapagliflozin l-proline in an immediate-release layer. The formulation and process of each layer were optimized using the QbD approach. A d-optimal mixture design and response surface design were applied to optimize critical material attributes and critical process parameters, respectively. The robust design space was developed using Monte Carlo simulations by evaluating the risk of uncertainty in the model predictions. Multivariate analysis showed that there were significant correlations among impeller speed, massing time, granule bulk density, and dissolution in the metformin HCl layer, and among roller pressure, ribbon density, and dissolution in the dapagliflozin l-proline layer. Process analytical technology (PAT) was used with in–line transmittance near-infrared spectroscopy to confirm the bulk and ribbon densities of the optimized bilayer tablet. Moreover, the in vitro drug release and in vivo pharmacokinetic studies showed that the optimized test drug was bioequivalent to the reference drug. This study suggested that integrated QbD, statistical, and PAT approaches can develop a robust control strategy for FDC bilayer tablets by implementing real-time release testing based on the relationships among various variables.

Comparison of calcium and hydroxyl ion release ability and in vivo apatite-forming ability of three bioceramic-containing root canal sealers

OBJECTIVE

Bioceramic-containing root canal sealers promote periapical healing via Ca²⁺ and OH^- release and apatite formation on the surface. This study aimed to compare Ca²⁺ and OH^- release and in vivo apatite formation of three bioceramic-containing root canal sealers: EndoSequence BC sealer (Endo-BC), MTA Fillapex (MTA-F), and Nishika Canal Sealer BG (N-BG).

MATERIALS AND METHODS

Polytetrafluoroethylene tubes filled with sealers were immersed in distilled water for 6 and 12 h and for 1, 7, 14, and 28 days to measure Ca²⁺ and OH^- release. Additionally, tubes filled with sealers were implanted in the backs of rats for 28 days, and in vivo apatite formation was analyzed using an electron probe microanalyzer.

RESULTS

Endo-BC released significantly more Ca²⁺ than the other sealers at 6 and 12 h and 1 day. Ca²⁺ release was significantly lower from N-BG than from Endo-BC and MTA-F at 14 and 28 days. OH^- release was significantly higher from Endo-BC than from the other sealers throughout the experiment, except at 1 day. OH^- release was lower from N-BG than from MTA-F at 6 h and 7 days. Only Endo-BC implants exhibited apatite-like calcium-, phosphorus-, oxygen-, and carbon-rich spherulites and apatite layer-like calcium- and phosphorus-rich, but radiopaque element-free, surface regions.

CONCLUSIONS

Ca²⁺ and OH^- release is ranked as follows: Endo-BC > MTA-F > N-BG. Only Endo-BC demonstrated in vivo apatite formation.

CLINICAL RELEVANCE

Endo-BC could promote faster periapical healing than MTA-F and N-BG.

Physicochemical Properties, Cytocompatibility, and Biocompatibility of a Bioactive Glass Based Retrograde Filling Material

The ideal retrograde filling material that is easy to handle, has good physicochemical properties, and is biocompatible has not yet been developed. The current study reports the development of a novel bioactive glass based powder for use as a retrograde filling material that is capable of altering the consistency and hardening rate of mixtures when mixed with existing bioactive glass based cement. Furthermore, its physicochemical properties, in vitro effects on human cementoblast-like cells, and in vivo effects on inflammatory responses were evaluated. The surface of the hardened cement showed the formation of hydroxyapatite-like precipitates and calcium and silicate ions were eluted from the cement when the pH level was stabilized at 10.5. Additionally, the cement was found to be insoluble and exhibited favorable handling properties. No adverse effects on viability, proliferation, and expression of differentiated markers were observed in the in vitro experiment, and the cement was capable of inducing calcium deposition in the cells. Moreover, the cement demonstrated a lower number of infiltrated inflammatory cells compared to the other materials used in the in vivo mouse subcutaneous implantation experiment. These findings suggest that the retrograde filling material composed of bioactive glass and the novel bioactive glass based powder exhibits favorable physicochemical properties, cytocompatibility, and biocompatibility.

The Structural, Physical, and In Vitro Biological Performance of Freshly Mixed and Set Endodontic Sealers

Objective:

The objective of this study was to evaluate the in vitro performance of endodontic sealers in their freshly mixed and set forms.

Methods:

The commercially used endodontic sealers (AH Plus, Dia-ProSeal, GuttaFlow 2, and Pulpdent Root Canal Sealer) were investigated and the chemical structure of freshly mixed and set sealers were assessed with Fourier transform infrared spectroscopy (FTIR). The surface morphology and elemental analysis were assessed with a scanning electron microscope (SEM) equipped with energy-dispersive X-ray spectroscopy. The pH and solubility analysis were performed and the cytotoxicity was done on extracts of freshly mixed and set materials using Alamar blue assay. One way ANOVA and Post Hoc Tukey analysis was used to do multiple comparison analysis of the mean values and standard deviation results through SPSS version 20 (IBM Software, NY, USA) for pH, solubility, and cytotoxicity analysis.

Results:

FTIR analysis revealed the structural pattern and the difference in freshly mixed and set samples was observed with the change in intensities of the peaks. The morphological pattern revealed the presence of micro/nano-particles with pores distributed throughout their structure. The sealer with the least solubility was AH Plus (0.10±0.01) followed by Dia-ProSeal (0.77±0.25), GuttaFlow 2 (1.88±0.82) and Pulpdent Root Canal Sealer (3.03±0.18). The solubility of AH plus was significantly lower (P<0.05) in comparison to GuttaFlow 2 and Pulpdent Root Canal Sealer. The highest pH (10.09±0.034) in the freshly mixed state and highest cytotoxicity in the freshly mixed (70.08±5.852) and set sealers (83.87±5.409) (P<0.05) at day 7 was observed in Dia-ProSeal. GuttaFlow 2 was the most biocompatible sealer in the set state and AH Plus was the most biocompatible sealer in the freshly mixed state at day 7.

Conclusion:

Clinically, the sealer is applied in fresh state, whereby this study signifies that which material is more biocompatible in fresh state and provides insight information to clinicians. AH Plus showed least solubility and cytocompatibility in fresh state compared to other groups.

Calcium Silicate-Based Biocompatible Light-Curable Dental Material for Dental Pulpal Complex

Dental caries causes tooth defects and clinical treatment is essential. To prevent further damage and protect healthy teeth, appropriate dental material is a need. However, the biocompatibility of dental material is needed to secure the oral environment. For this purpose, biocompatible materials were investigated for incorporated with dental capping material. Among them, nanomaterials are applied to dental materials to enhance their chemical, mechanical, and biological properties. This research aimed to study the physicochemical and mechanical properties and biocompatibility of a recently introduced light-curable mineral trioxide aggregate (MTA)-like material without bisphenol A-glycidyl methacrylate (Bis-GMA). To overcome the compromised mechanical properties in the absence of Bis-GMA, silica nanoparticles were synthesized and blended with a dental polymer for the formation of a nano-network. This material was compared with a conventional light-curable MTA-like material that contains Bis-GMA. Investigation of the physiochemical properties followed ISO 4049. Hydroxyl and calcium ion release from the materials was measured over 21 days. The Vickers hardness test and three-point flexural strength test were used to assess the mechanical properties. Specimens were immersed in solutions that mimicked human body plasma for seven days, and surface characteristics were analyzed. Biological properties were assessed by cytotoxicity and biomineralization tests. There was no significant difference between the tested materials with respect to overall physicochemical properties and released calcium ions. The newly produced material released more calcium ions on the third day, but 14 days later, the other material containing Bis-GMA released higher levels of calcium ions. The microhardness was reduced in a low pH environment, and differences between the specimens were observed. The flexural strength of the newly developed material was significantly higher, and different surface morphologies were detected. The recently produced extract showed higher cell viability at an extract concentration of 100%, while mineralization was clear at the conventional concentration of 25%. No significant changes in the physical properties between Bis-GMA incorporate material and nanoparticle incorporate materials.